637 results on '"Rebohle, L."'
Search Results
2. Thermal stability of Te-hyperdoped Si: Atomic-scale correlation of the structural, electrical and optical properties
- Author
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Wang, Mao, Hubner, R., Xie, Chi Xu Yufang, Berencen, Y., Heller, R., Rebohle, L., Helm, M., Prucnal, S., and Zhou, Shengqiang
- Subjects
Physics - Applied Physics - Abstract
Si hyperdoped with chalcogens (S, Se, Te) is well-known to possess unique properties such as an insulator-to-metal transition and a room-temperature sub-bandgap absorption. These properties are expected to be sensitive to a post-synthesis thermal annealing, since hyperdoped Si is a thermodynamically metastable material. Thermal stability of the as-fabricated hyperdoped Si is of great importance for the device fabrication process involving temperature-dependent steps like ohmic contact formation. Here, we report on the thermal stability of the as-fabricated Te-hyperdoped Si subjected to isochronal furnace anneals from 250 {\deg}C to 1200 {\deg}C. We demonstrate that Te-hyperdoped Si exhibits thermal stability up to 400 {\deg}C with a duration of 10 minutes that even helps to further improve the crystalline quality, the electrical activation of Te dopants and the room-temperature sub-band gap absorption. At higher temperatures, however, Te atoms are found to move out from the substitutional sites with a migration energy of EM = 2.1+/-0.1 eV forming inactive clusters and precipitates that impair the structural, electrical and optical properties. These results provide further insight into the underlying physical state transformation of Te dopants in a metastable compositional regime caused by post-synthesis thermal annealing as well as pave the way for the fabrication of advanced hyperdoped Si-based devices.
- Published
- 2019
- Full Text
- View/download PDF
3. Breaking the doping limit in silicon by deep impurities
- Author
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Wang, Mao, Debernardi, A., Berencén, Y., Heller, R., Xu, Chi, Yuan, Ye, Xie, Yufang, Böttger, R., Rebohle, L., Skorupa, W., Helm, M., Prucnal, S., and Zhou, Shengqiang
- Subjects
Condensed Matter - Materials Science - Abstract
N-type doping in Si by shallow impurities, such as P, As and Sb, exhibits an intrinsic limit due to the Fermi-level pinning via defect complexes at high doping concentrations. Here we demonstrate that doping Si with the chalcogen Te by non-equilibrium processing, a deep double donor, can exceed this limit and yield higher electron concentrations. In contrast to shallow impurities, both the interstitial Te fraction decreases with increasing doping concentration and substitutional Te dimers become the dominant configuration as effective donors, leading to a non-saturating carrier concentration as well as to an insulator-to-metal transition. First-principle calculations reveal that the Te dimers possess the lowest formation energy and donate two electrons per dimer to the conduction band. These results provide novel insight into physics of deep impurities and lead to a possible solution for the ultra-high electron concentration needed in today's Si-based nanoelectronics., Comment: 26 pages, including the suppl information
- Published
- 2018
- Full Text
- View/download PDF
4. Extended Infrared Photoresponse in Te-Hyperdoped Si at Room Temperature
- Author
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Wang, Mao, Berencén, Y., García-Hemme, E., Prucnal, S., Hübner, R., Yuan, Ye, Xu, Chi, Rebohle, L., Böttger, R., Heller, R., Schneider, H., Skorupa, W., Helm, M., and Zhou, Shengqiang
- Subjects
Condensed Matter - Materials Science - Abstract
Presently, silicon photonics requires photodetectors that are sensitive in a broad infrared range, can operate at room temperature, and are suitable for integration with the existing Si-technology process. Here, we demonstrate strong room-temperature sub-band-gap photoresponse of photodiodes based on Si hyperdoped with tellurium. The epitaxially recrystallized Te-hyperdoped Si layers are developed by ion implantation combined with pulsed-laser melting and incorporate Te-dopant concentrations several orders of magnitude above the solid solubility limit. With increasing Te concentration, the Te-hyperdoped layer changes from insulating to quasi-metallic behavior with a finite conductivity as the temperature tends to zero. The optical absorptance is found to increase monotonically with increasing Te concentration and extends well into the mid-infrared range. Temperature-dependent optoelectronic photoresponse unambiguously demonstrates that the extended infrared photoresponsivity from Te-hyperdoped Si p-n photodiodes is mediated by a Te intermediate band within the upper half of the Si band gap. This work contributes to pave the way toward establishing a Si-based broadband infrared photonic system operating at room temperature., Comment: 18 pages, 7 figures
- Published
- 2018
- Full Text
- View/download PDF
5. Realizing the insulator-to-metal transition in Se-hyperdoped Si via non-equilibrium material processing
- Author
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Liu, F., Prucnal, S., Berencén, Y., Zhang, Z., Yuan, Y., Liu, Y., Heller, R., Boettger, R., Rebohle, L., Skorupa, W., Helm, M., and Zhou, S.
- Subjects
Condensed Matter - Materials Science - Abstract
We report on the insulator-to-metal transition in Se-hyperdoped Si layers driven by manipulating the Se concentration via non-equilibrium material processing, i.e. ion implantation followed by millisecond-flash lamp annealing. Electrical transport measurements reveal an increase of carrier concentration and conductivity with increasing Se concentration. For the semi-insulating sample with Se concentrations below the Mott limit, quantitative analysis of the temperature dependence of conductivity indicates a variable-range hopping mechanism with an exponent of s = 1/2 rather than 1/4, which implies a Coulomb gap at the Fermi level. The observed insulator-to-metal transition is attributed to the formation of an intermediate band in the Se-hyperdoped Si layers., Comment: 10 pages, 4 figures, accepted by J. Phys. D: Appl. Phys
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- 2017
- Full Text
- View/download PDF
6. Bandgap narrowing in Mn doped GaAs probed by room-temperature photoluminescence
- Author
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Prucnal, S., Gao, K., Skorupa, I., Rebohle, L., Vines, L., Schmidt, H., Khalid, M., Wang, Y., Weschke, E., Skorupa, W., Grenzer, J., Huebner, R., Helm, M., and Zhou, S.
- Subjects
Condensed Matter - Materials Science - Abstract
The electronic band structure of the (Ga,Mn)As system has been one of the most intriguing problems in solid state physics over the past two decades. Determination of the band structure evolution with increasing Mn concentration is a key issue to understand the origin of ferromagnetism. Here we present room temperature photoluminescence and ellipsometry measurements of Ga_{100%-x}Mn_{x}As alloy. The up-shift of the valence-band is proven by the red shift of the room temperature near band gap emission from the Ga_{100%-x}Mn_{x}As alloy with increasing Mn content. It is shown that even a doping by 0.02 at.% of Mn affects the valence-band edge and it merges with the impurity band for a Mn concentration as low as 0.6 at.%. Both X-ray diffraction pattern and high resolution cross-sectional TEM images confirmed full recrystallization of the implanted layer and GaMnAs alloy formation., Comment: 24 pages, 7 figures, accepted at Phys. Rev. B 2015
- Published
- 2015
- Full Text
- View/download PDF
7. Si1-x-yGeySnx alloy formation by Sn ion implantation and flash lamp annealing
- Author
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Steuer, O., Michailow, M., (0000-0002-5200-6928) Hübner, R., Pyszniak, K., Turek, M., (0000-0001-5295-2554) Kentsch, U., (0009-0003-0366-9690) Ganss, F., Khan, M. M., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Knoch, J., Helm, M., Cuniberti, G., (0000-0002-3146-8031) Georgiev, Y., (0000-0002-4088-6032) Prucnal, S., Steuer, O., Michailow, M., (0000-0002-5200-6928) Hübner, R., Pyszniak, K., Turek, M., (0000-0001-5295-2554) Kentsch, U., (0009-0003-0366-9690) Ganss, F., Khan, M. M., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Knoch, J., Helm, M., Cuniberti, G., (0000-0002-3146-8031) Georgiev, Y., and (0000-0002-4088-6032) Prucnal, S.
- Abstract
For many years, Si1-yGey alloys have been applied in the semiconductor industry due to the ability to adjust the performance of Si-based nanoelectronic devices. Following this alloying approach of group-IV semiconductors, adding tin into the alloy appears as the obvious next step, which leads to additional possibilities for tailoring the material properties. Adding Sn enables effective band gap and strain engineering and can improve the carrier mobilities, which makes Si1-x-yGeySnx alloys promising candidates for future opto- and nanoelectronics applications. The bottom-up approach for epitaxial growth of Si1-x-yGeySnx, e.g., by chemical vapor deposition and molecular beam epitaxy, allows tuning the material properties in the growth direction only; the realization of local material modifications to generate lateral heterostructures with a such a bottom up approach is extremely elaborate since it would require the use of lithography, etching and either selective epitaxy or epitaxy and chemical-mechanical polishing giving rise to interface issues, non-planar substrates etc. This article shows the possibility of fabricating Si1-x-yGeySnx alloys by Sn implantation into Si1-yGey layers followed by millisecond-range flash lamp annealing. The materials are investigated by Rutherford backscattering spectrometry, micro Raman spectroscopy, X-ray diffraction, and transmission electron microscopy. The fabrication approach was adapted to ultra-thin Si1-yGey layers on silicon-on-insulator substrates. Finally, we show the possibility of implanting Sn locally in ultra-thin Si1-yGey films. We demonstrate the realization of vertical AND lateral Si1-x-yGeySnx heterostructures by tin ion implantation and flash lamp annealing.
- Published
- 2024
8. Data publication: Formation of martensitic microstructure in epitaxial Ni-Mn-Ga films after fast cooling
- Author
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(0000-0002-3977-2505) Ge, Y., (0009-0003-0366-9690) Ganss, F., (0000-0003-3309-7948) Lünser, K., (0000-0003-1352-8026) Kar, S., (0000-0002-5200-6928) Hübner, R., (0000-0002-4885-799X) Zhou, S., (0000-0002-8066-6392) Rebohle, L., (0000-0001-9450-4952) Fähler, S., (0000-0002-3977-2505) Ge, Y., (0009-0003-0366-9690) Ganss, F., (0000-0003-3309-7948) Lünser, K., (0000-0003-1352-8026) Kar, S., (0000-0002-5200-6928) Hübner, R., (0000-0002-4885-799X) Zhou, S., (0000-0002-8066-6392) Rebohle, L., and (0000-0001-9450-4952) Fähler, S.
- Abstract
Raw data for the publication titled 'Formation of martensitic microstructure in epitaxial Ni-Mn-Ga films after fast cooling' done by Yuru Ge (FWIN-HZDR) and the colleagues. The order of the figures follows the latest manuscript version before submission, labeled "v13".
- Published
- 2024
9. NiGe formation on thin Ge films by flash lamp annealing: electrical properties
- Author
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Begeza, V., (0000-0002-8066-6392) Rebohle, L., Stöcker, H., Mehner, E., (0000-0002-5200-6928) Hübner, R., (0000-0002-4885-799X) Zhou, S., Begeza, V., (0000-0002-8066-6392) Rebohle, L., Stöcker, H., Mehner, E., (0000-0002-5200-6928) Hübner, R., and (0000-0002-4885-799X) Zhou, S.
- Abstract
Flash lamp annealing (FLA) is an ultra-short annealing method which excellently meets the requirements of thin film processing and has already been used in microelectronics. Due to the relatively high hole mobility, thin Ge layers are highly interesting as a transistor channel material or generally as a functional layer both in CMOS technology and in the field of low-cost electronics. One possibility to realize ohmic contacts with low contact resistance is the use of metal germanides, especially the stoichiometric NiGe phase. In this work, NiGe contacts on thin Ge films were fabricated by magnetron sputtering followed by FLA. The evolution of microstructure with increasing thermal budget was traced by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The electrical measurements focus on the determination of contact resistance by the circular transfer length method (cTLM). The contacts were fabricated by two different approaches, and the influence of different process steps on layer morphology and the uncertainty of the measurement was studied.
- Published
- 2024
10. Extended infrared photoresponse in Te-hyperdoped Si at room temperature
- Author
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Wang, Mao, Berencén, Yonder, García Hemme, Eric, Prucnal, S., Hübner, R., Yuan, Ye, Xu, Chi, Rebohle, L., Böttger, R., Heller, R., Schneider, H., Skorupa, W., Helm, M., Zhou, Shengqiang, Wang, Mao, Berencén, Yonder, García Hemme, Eric, Prucnal, S., Hübner, R., Yuan, Ye, Xu, Chi, Rebohle, L., Böttger, R., Heller, R., Schneider, H., Skorupa, W., Helm, M., and Zhou, Shengqiang
- Abstract
Presently, silicon photonics requires photodetectors that are sensitive in a broad infrared range, can operate at room temperature, and are suitable for integration with the existing Si-technology process. Here, we demonstrate strong room-temperature sub-band-gap photoresponse of photodiodes based on Si hyperdoped with tellurium. The epitaxially recrystallized Te-hyperdoped Si layers are developed by ion implantation combined with pulsed-laser melting and incorporate Te-dopant concentrations several orders of magnitude above the solid solubility limit. With increasing Te concentration, the Te-hyperdoped layer changes from insulating to quasi-metallic behavior with a finite conductivity as the temperature tends to zero. The optical absorptance is found to increase monotonically with increasing Te concentration and extends well into the mid-infrared range. Temperature-dependent optoelectronic photoresponse unambiguously demonstrates that the extended infrared photoresponsivity from Te-hyperdoped Si p-n photodiodes is mediated by a Te intermediate band within the upper half of the Si band gap. This work contributes to pave the way toward establishing a Si-based broadband infrared photonic system operating at room temperature., Ministerio de Economía y Competitividad (España), Structural Characterization Facilities at Ion Beam Center, Federal Ministry of Education & Research, Alexander von Humboldt Foundation, Helmholtz Association, China Scholarship Council, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub
- Published
- 2024
11. Flash lamp annealing for roll-to-roll applications
- Author
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(0000-0002-8066-6392) Rebohle, L., Begeza, V., Cherkouk, C., (0000-0002-5466-334X) Folgner, C., (0000-0002-4088-6032) Prucnal, S., (0000-0002-4885-799X) Zhou, S., (0000-0002-8066-6392) Rebohle, L., Begeza, V., Cherkouk, C., (0000-0002-5466-334X) Folgner, C., (0000-0002-4088-6032) Prucnal, S., and (0000-0002-4885-799X) Zhou, S.
- Abstract
The talk gives a short overview about the combination of flash lamp annealing and roll-to-roll applications including the application fields of inkjet printing with nanoparticle inks, transparent conduction oxides, and energy materials.
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- 2024
12. Inkjet printing of functional materials activated by ms-range flash lamp annealing
- Author
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(0000-0002-5466-334X) Folgner, C., Zhang, G., Prucnal, S., Rebohle, L., Zhou, S., (0000-0002-5466-334X) Folgner, C., Zhang, G., Prucnal, S., Rebohle, L., and Zhou, S.
- Abstract
Currently, we observe a continuous need for innovative flexible optoelectronics that are present in smart homes, smart healthcare products and different sensors like gas or temperature sensors. All those applications require a fast and cheap fabrication process. In the last two decades, flash lamp annealing (FLA or photonic curing) has extended its scope of applications from traditional microelectronics to many other areas where thin film coatings are in use. The layer deposition by inkjet printing followed by FLA, preferably on flexible substrates, features a couple of advantages such as material savings, no need for lithographic structuring processes, a fast adaption to changing design requirements and easy possibility for up-scaling. In the case of nanoparticle-based inks, FLA has not only the task to evaporate remnants of the solvent, the binder and other additives, and to sinter the nanoparticles, but has advantageous in terms of energy and process time saving [1]. Currently, we are putting a roll-to-roll (R2R) tool combining inkjet printing and FLA into operation, and first successful tests to print nanoparticle inks containing transparent conductive oxides for optoelectronic applications (TCOs) like zinc oxide (ZnO), aluminum doped zinc oxide (AZO) and also metal inks like copper oxide/copper (CuO/Cu) followed by ex-situ FLA have been done. In this poster, we will report some of these first results and discuss the corresponding application cases. In addition, the extension of the palette of available materials will address further application, as we will discuss in the case of Si, which e.g. is of high interest as anode material for LIBs and electronic devices in the area of low-cost or printed electronics.
- Published
- 2024
13. Thin Film Lithium-Ion Battery Based on Copper Silicon Anode
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Cherkouk, C., Weigel, T., Köhler, T., Stöcker, H., Ferch, M., Hahn, R., Delan, A., Folgner, C., Zhou, S., Rebohle, L., Cherkouk, C., Weigel, T., Köhler, T., Stöcker, H., Ferch, M., Hahn, R., Delan, A., Folgner, C., Zhou, S., and Rebohle, L.
- Abstract
Ongoing miniaturization down to a few nanometers will lead to further significant reductions in the power consumption of microchips and sensors. The number of innovative applications immediately arise from the potential of integrating a microbattery as a power source for flexible electronics, wearables, the Internet of Things, medical implants and sensor chips. In this work, a thin film lithium-Ion battery (TF-LIB) is demonstrated. The TF-LIB consists of a high potential copper silicide anode (CuSi-anode) that can be integrated on a Siwafer with standard semiconductor technology and a hybrid polymer electrolyte with a high lithium-ion transference number. Two cathode materials were tested: LiFePO4 and NCA. The CuSi-anode is fabricated by Si sputtering followed by flash lamp annealing (FLA). This anode material replaces metallic lithium for reaching high energy densities and provides the thermal stability required in microelectronics (> 230 °C for soldering). The hybrid polymer electrolyte is mechanically stable against the volume change of the silicon during the lithiation/ delithiathion processes. The electrolyte is unreactive and thermally stable at high temperatures during operation.
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- 2024
14. Determination of the thermal cycle during flash lamp annealing without a direct temperature measurement
- Author
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Rebohle, L., Neubert, M., Schumann, T., and Skorupa, W.
- Published
- 2018
- Full Text
- View/download PDF
15. Bound-to-bound and bound-to-continuum optical transitions in combined quantum dot - superlattice systems
- Author
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Schrey, F. F., Rebohle, L., Mueller, T., Strasser, G., Unterrainer, K., Nguyen, D. P., Regnault, N., Ferreira, R., and Bastard, G.
- Subjects
Condensed Matter - Other Condensed Matter - Abstract
By combining band gap engineering with the self-organized growth of quantum dots, we present a scheme of adjusting the mid-infrared absorption properties to desired energy transitions in quantum dot based photodetectors. Embedding the self organized InAs quantum dots into an AlAs/GaAs superlattice enables us to tune the optical transition energy by changing the superlattice period as well as by changing the growth conditions of the dots. Using a one band envelope function framework we are able, in a fully three dimensional calculation, to predict the photocurrent spectra of these devices as well as their polarization properties. The calculations further predict a strong impact of the dots on the superlattices minibands. The impact of vertical dot alignment or misalignment on the absorption properties of this dot/superlattice structure is investigated. The observed photocurrent spectra of vertically coupled quantum dot stacks show very good agreement with the calculations.In these experiments, vertically coupled quantum dot stacks show the best performance in the desired photodetector application., Comment: 8 pages, 10 figures, submitted to PRB
- Published
- 2004
- Full Text
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16. Silicon anode processing using flash lamp annealing for lithium ion batteries
- Author
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Cherkouk, C., Folgner, C., Worbs, A., (0000-0002-5200-6928) Hübner, R., (0000-0002-4088-6032) Prucnal, S., Schumann, T., Krüger, S., (0000-0002-4885-799X) Zhou, S., (0000-0002-8066-6392) Rebohle, L., Cherkouk, C., Folgner, C., Worbs, A., (0000-0002-5200-6928) Hübner, R., (0000-0002-4088-6032) Prucnal, S., Schumann, T., Krüger, S., (0000-0002-4885-799X) Zhou, S., and (0000-0002-8066-6392) Rebohle, L.
- Abstract
In the near future, silicon will play a key role as anode material for rechargeable lithium ion batteries (LIBs). It shows a low discharge potential and an extremely high specific theoretical capacity of about 4200 mAhg-1 in comparison to that of graphite with a theoretical capacity of 370 mAhg-1. However, the intrinsic volume change of Si particles of more than 400 % during the lithiation and delithiation processes hinders the Si to fully replace the conventional graphite in commercial LIBs. Using planar flash-lamp annealing (FLA) with annealing times in the sub-second range directly after the deposition of a Si thin film on a copper foil, we fabricated a copper silicide anode (CuSi-anode) with outstanding electrical and electrochemical properties. Herein, structural investigations using scanning electron microscopy and X-ray diffraction show a Cu-mediated silicidation at generating mixed phases of copper silicides, SiOx, Cu, and Si nanoparticles. The performance of battery cells with CuSi-anode having a Si thickness of 5 µm versus LiFePO4 shows a surface capacity of 2mAh/cm2 over 100 cycles with capacity loss in the course of cycling but with good electrical conductivity between the anode and current collector. Finally, we compare the electrochemical performance of the CuSi-anode with a conventional graphite anode at the same cell configuration and chemical conditions.
- Published
- 2023
17. Near-infrared photodetectors based on single germanium nanowires
- Author
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(0000-0002-2708-2718) Echresh, A., (0000-0002-7958-4306) Shaikh, M. S., Helm, M., (0000-0001-6368-8728) Erbe, A., (0000-0003-3529-0207) Berencen, Y., (0000-0002-8066-6392) Rebohle, L., (0000-0002-3146-8031) Georgiev, Y., (0000-0002-2708-2718) Echresh, A., (0000-0002-7958-4306) Shaikh, M. S., Helm, M., (0000-0001-6368-8728) Erbe, A., (0000-0003-3529-0207) Berencen, Y., (0000-0002-8066-6392) Rebohle, L., and (0000-0002-3146-8031) Georgiev, Y.
- Abstract
Germanium (Ge) is a promising candidate for designing near-infrared photodetectors because of its bandgap (0.66 eV), which induces a large absorption coefficient at near-infrared wavelengths. Also, Ge has excellent compatibility of parallel processing with silicon technology [1,2]. Photodetectors based on Ge material have been fabricated with different structures such as metal-semiconductor-metal (MSM) and p−n junctions. On the other hand, the observation of high responsivity in semiconductor nanowires with a high surface-to-volume ratio has attracted growing interest in using nanowires in photodetectors. So far, significant efforts have been made to fabricate single nanowire-based photodetectors with different materials such as Si, Ge, and GaN to achieve miniaturized devices with high responsivity and short response time [3-5]. Hence, Ge nanowires are an excellent candidate to fabricate single nanowire-based near-infrared photodetectors. In this work, we report on the fabrication and characterization of an axial p−n junction along Ge nanowires. First, through a resist mask created by electron beam lithography (EBL), the top Ge layers of germanium-on-insulator (GeOI) substrates were locally doped with phosphorus ions using ion beam implantation followed by rear-side flash lamp annealing. Then, the single Ge nanowire-based photodetectors containing an axial p−n junction were fabricated using EBL and inductively coupled plasma reactive ion etching. The fabricated single Ge nanowire devices demonstrate the rectifying current−voltage characteristic of a p−n diode in dark conditions. Moreover, the photoresponse of the axial p−n junction-based photodetectors was investigated under light illumination with three different wavelengths: 637 nm, 785 nm, and 1550 nm. The measurements indicated that the fabricated photodetectors can be operated at zero bias and room temperature under ambient conditions. A high responsivity of 3.7×102 AW-1 and a detectivity of 1.9×1013 cmHz1/2W-1
- Published
- 2023
18. Post growth thermal treatments of Si1-x-yGexSny alloys
- Author
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Steuer, O., Schwarz, D., Oehme, M., (0000-0002-5200-6928) Hübner, R., Ganss, F., Khan, M. M., Cheng, Y., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Helm, M., Cuniberti, G., (0000-0002-3146-8031) Georgiev, Y., (0000-0002-4088-6032) Prucnal, S., Steuer, O., Schwarz, D., Oehme, M., (0000-0002-5200-6928) Hübner, R., Ganss, F., Khan, M. M., Cheng, Y., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Helm, M., Cuniberti, G., (0000-0002-3146-8031) Georgiev, Y., and (0000-0002-4088-6032) Prucnal, S.
- Abstract
Si1-x-yGexSny alloys are promising materials for future applications in opto- and nanoelectronics. These alloys enable effective band gap engineering, a broad adjustability of the lattice parameter, exhibit much higher carrier mobility than pure Si and are compatible with CMOS technology. Unfortunately, the equilibrium solid solubility of Sn in Si1-xGex is less than 1% and pseudomorphic growth of Si1-xyGexSny on Ge or Si causes in-plane compressive strain in the grown layer, which degrades the superior properties of the alloys. Therefore, the post-growth strain engineering using ultrafast non-equilibrium thermal treatments like flash lamp annealing (FLA) or pulsed laser annealing (PLA) to improve the layer quality is needed. In this contribution, we discuss the influence of millisecond FLA and nanosecond PLA on Si1-x-yGexSny alloys and present an efficient way to improve the layer quality of thin film Si1-x-yGexSny on insulator by PLA. Different Si1-xyGexSny alloys are directly grown on commercial silicon-on-insulator (SOI) wafers and treated by FLA or PLA. The material is analysed by micro-Raman spectroscopy, Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD) before and after the thermal treatments. It is shown that after annealing, the material is single-crystalline with much better crystallinity than the as-grown layer.
- Published
- 2023
19. NiGe formation on thin Ge films by flash lamp annealing: electrical properties
- Author
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Begeza, V., (0000-0002-8066-6392) Rebohle, L., Stöcker, H., Mehner, E., (0000-0002-5200-6928) Hübner, R., (0000-0002-4885-799X) Zhou, S., Begeza, V., (0000-0002-8066-6392) Rebohle, L., Stöcker, H., Mehner, E., (0000-0002-5200-6928) Hübner, R., and (0000-0002-4885-799X) Zhou, S.
- Abstract
Flash lamp annealing (FLA) is an ultra-short annealing method which excellently meets the requirements of thin film processing and has already been used in microelectronics. Due to the relatively high hole mobility, thin Ge layers are highly interesting as a transistor channel material or generally as a functional layer both in CMOS technology and in the field of low-cost electronics. One possibility to realize ohmic contacts with low contact resistance is the use of metal germanides, especially the stoichiometric NiGe phase. In this work, NiGe contacts on thin Ge films were fabricated by magnetron sputtering followed by FLA. The evolution of microstructure with increasing thermal budget was traced by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The electrical measurements focus on the determination of contact resistance by the circular transfer length method (cTLM). The contacts were fabricated by two different approaches, and the influence of different process steps on layer morphology and the uncertainty of the measurement was studied.
- Published
- 2023
20. NiGe formation on thin Ge films by flash lamp annealing
- Author
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Begeza, V., (0000-0002-8066-6392) Rebohle, L., Stöcker, H., Mehner, E., (0000-0002-5200-6928) Hübner, R., (0000-0002-4885-799X) Zhou, S., Begeza, V., (0000-0002-8066-6392) Rebohle, L., Stöcker, H., Mehner, E., (0000-0002-5200-6928) Hübner, R., and (0000-0002-4885-799X) Zhou, S.
- Abstract
In this work, NiGe contacts on thin Ge films were fabricated by magnetron sputtering followed by flash lamp annealing (FLA). The evolution of microstructure with increasing thermal budget was traced by transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The film sheet resistance, the free charge carrier mobility and concentration, and the contact resistance were measured by the four-point-probe method, by Hall effect measurements, and by the circular transfer length method, respectively. Based on this data, the formation process of NiGe contacts during FLA is described, which passes through a stage of Ni-rich phases with high electrical resistivity, before the final stoichiometric NiGe phase is formed.
- Published
- 2023
21. Post growth thermal treatments of Silicon-Germanium-Tin-on-insulator alloys
- Author
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Steuer, O., Schwarz, D., Oehme, M., (0000-0002-5200-6928) Hübner, R., (0009-0003-0366-9690) Ganss, F., Khan, M. M., Cheng, Y., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Helm, M., Cuniberti, G., (0000-0002-3146-8031) Georgiev, Y., (0000-0002-4088-6032) Prucnal, S., Steuer, O., Schwarz, D., Oehme, M., (0000-0002-5200-6928) Hübner, R., (0009-0003-0366-9690) Ganss, F., Khan, M. M., Cheng, Y., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Helm, M., Cuniberti, G., (0000-0002-3146-8031) Georgiev, Y., and (0000-0002-4088-6032) Prucnal, S.
- Abstract
Si1-x-yGexSny alloys are promising materials for future applications in opto- and nanoelectronics. These alloys enable effective band gap engineering, a broad adjustability of the lattice parameter, exhibit much higher carrier mobility than pure Si and are compatible with CMOS technology. Unfortunately, the equilibrium solid solubility of Sn in Si1-xGex is less than 1% and pseudomorphic growth of Si1-xyGexSny on Ge or Si causes in-plane compressive strain in the grown layer, which degrades the superior properties of the alloys. Therefore, the post-growth strain engineering using ultrafast non-equilibrium thermal treatments like flash lamp annealing (FLA) or pulsed laser annealing (PLA) to improve the layer quality is needed. In this contribution, we discuss the influence of millisecond FLA and nanosecond PLA on Si1-x-yGexSny alloys and present an efficient way to improve the layer quality of thin film Si1-x-yGexSny on insulator by PLA. Different Si1-xyGexSny alloys are directly grown on commercial silicon-on-insulator (SOI) wafers and treated by FLA or PLA. The material is analysed by micro-Raman spectroscopy, Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD) before and after the thermal treatments. It is shown that after annealing, the material is single-crystalline with much better crystallinity than the as-grown layer.
- Published
- 2023
22. Defect landscape in TiO2 after ms-range annealing and resulting photocatalytic efficiency
- Author
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(0000-0001-7933-7295) Liedke, M. O., (0000-0002-4088-6032) Prucnal, S., (0000-0003-3674-0767) Butterling, M., (0000-0001-5782-9627) Hirschmann, E., Gago, R., David, G. C., Rebohle, L., Helm, M., (0000-0002-4885-799X) Zhou, S., (0000-0001-7575-3961) Wagner, A., (0000-0001-7933-7295) Liedke, M. O., (0000-0002-4088-6032) Prucnal, S., (0000-0003-3674-0767) Butterling, M., (0000-0001-5782-9627) Hirschmann, E., Gago, R., David, G. C., Rebohle, L., Helm, M., (0000-0002-4885-799X) Zhou, S., and (0000-0001-7575-3961) Wagner, A.
- Abstract
Transition metal oxides, particularly TiO2, are photoactive materials, which can be utilized to clean the air from pollutants and to produce green hydrogen for clean energy at the same time. They are one of the most promising candidates for high-performance photocatalysis. In this work, we investigate the effect of 20 ms flash lamp annealing (FLA) of sputter deposited TiO2, where arising from the light irradiation structural modifications of the films facilitates the photocatalytic (PC) degradation of two chemical compounds, namely methyl blue and methyl orange, once they interact with the surface of TiO2. The precise control of the flash energy input enables tuning of the TiO2 phase formation starting from pure anatase to mixed anatase/rutile phases, the latter associated with increased PC effect. Scanning electron microscopy and X-ray diffraction studies show that the crystal size and film quality increase with increasing annealing temperature. Further, the evolution of structural defects after FLA has been assessed by positron annihilation spectroscopy (PAS) and photoluminescence. Positron annihilation lifetime characteristics, i.e., positron lifetimes and their relative intensities profoundly sketch a transition between pure anatase and emerging rutile phase as a function of flash energy. Vacancy complexes close to the size of trivacancy dominate the anatase phase, whereas in the mixed anatase/rutile phase smaller open volume is evidenced, likely as a direct consequence of annealing. Finally, Doppler broadening PAS indicates the overall reduction of defect density exhibiting a similar transient phase region at the intermediate flash energies.
- Published
- 2023
23. On-chip lateral Si:Te PIN photodiodes for room-temperature detection in the telecom optical wavelength bands
- Author
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(0000-0002-7958-4306) Shaikh, M. S., Wen, S., Catuneanu, M.-T., (0000-0003-4606-7203) Wang, M., (0000-0001-6368-8728) Erbe, A., (0000-0002-4088-6032) Prucnal, S., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Jamshidi, K., Helm, M., (0000-0003-3529-0207) Berencen, Y., (0000-0002-7958-4306) Shaikh, M. S., Wen, S., Catuneanu, M.-T., (0000-0003-4606-7203) Wang, M., (0000-0001-6368-8728) Erbe, A., (0000-0002-4088-6032) Prucnal, S., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Jamshidi, K., Helm, M., and (0000-0003-3529-0207) Berencen, Y.
- Abstract
Photonic integrated circuits require photodetectors that operate at room temperature with sensitivity at telecom wavelengths and are suitable for integration with planar complementary-metal-oxide-semiconductor (CMOS) technology. Silicon hyperdoped with deep-level impurities is a promising material for silicon infrared detectors because of its strong room-temperature photoresponse in the short-wavelength infrared region caused by the creation of an impurity band within the silicon band gap. In this work, we present the first experimental demonstration of lateral Te-hyperdoped Si PIN photodetectors operating at room temperature in the optical telecom bands. We provide a detailed description of the fabrication process, working principle, and performance of the photodiodes, including their key figure of merits. Our results are promising for the integration of active and passive photonic elements on a single Si chip, leveraging the advantages of planar CMOS technology.
- Published
- 2023
24. TiO2 phase engineering by millisecond range annealing for highly efficient photocatalysis
- Author
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(0000-0002-4088-6032) Prucnal, S., Gago, R., Gonzales Calatayud, D., Rebohle, L., Oskar Liedke, M., Butterling, M., Wagner, A., Helm, M., Zhou, S., (0000-0002-4088-6032) Prucnal, S., Gago, R., Gonzales Calatayud, D., Rebohle, L., Oskar Liedke, M., Butterling, M., Wagner, A., Helm, M., and Zhou, S.
- Abstract
Air pollution and the energy crisis are the two main driving forces behind the development of alternative, environmentally friendly methods of energy production. Photoactive materials can be used both to clean the air and to produce green hydrogen for clean energy. Transition metal oxides are one of the most considered materials for high-performance photocatalysis. In this work, we investigate the effect of millisecond flash lamp annealing (FLA) of TiO2 on the degradation of methyl blue (MB) and methyl orange (MO). To reduce the energy consumption of the TiO2 deposition process, the layers were made using magnetron sputtering at room temperature, followed by millisecond FLA. By controlling the flash energy input, we can tune the phase formation of TiO2 films from pure anatase to mixed anatase/rutile phases. Scanning electron microscopy, positron annihilation spectroscopy, photoluminescence and X-ray diffraction studies show that the crystal size and film quality increase with increasing annealing temperature. Photocatalytic experiments demonstrate that FLA-treated TiO2 films are active in degrading both MB and MO. This makes them attractive not only for the production of green hydrogen, but also for the purification of water from medical contaminants.
- Published
- 2023
25. B20 Weyl semimetal CoSi film fabricated by flash-lamp annealing
- Author
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Li, Z., Yuan, Y., Hübner, R., (0000-0002-8066-6392) Rebohle, L., Zhou, Y., Helm, M., Nielsch, K., (0000-0002-4088-6032) Prucnal, S., (0000-0002-4885-799X) Zhou, S., Li, Z., Yuan, Y., Hübner, R., (0000-0002-8066-6392) Rebohle, L., Zhou, Y., Helm, M., Nielsch, K., (0000-0002-4088-6032) Prucnal, S., and (0000-0002-4885-799X) Zhou, S.
- Abstract
B20-CoSi is a newly discovered Weyl semimetal that crystallizes into a non-centrosymmetric crystal structure. However, the investigation of B20-CoSi has so far been focused on bulk materials, whereas the growth of thin films on technology-relevant substrates is a prerequisite for most practical applications. In this study, we have used millisecond-range flash-lamp annealing, a non-equilibrium solid-state reaction, to grow B20-CoSi thin films. By optimizing the annealing parameters, we were able to obtain thin films with a pure B20-CoSi phase. The magnetic and transport measurements indicate the appearance of the charge density wave and the chiral anomaly. Our work presents a promising method for preparing thin films of most binary B20 transition-metal silicides, which are candidates for topological Weyl semimetals.
- Published
- 2023
26. TiO2 phase engineering by millisecond range annealing for highly efficient photocatalysis
- Author
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Prucnal, S., Gago, R., Gonzales Calatayud, D., Rebohle, L., Oskar Liedke, M., Butterling, M., Wagner, A., Helm, M., and Zhou, S.
- Subjects
flash lamp annealing ,TiO2 ,methyl blue ,photocatalysis - Abstract
Air pollution and the energy crisis are the two main driving forces behind the development of alternative, environmentally friendly methods of energy production. Photoactive materials can be used both to clean the air and to produce green hydrogen for clean energy. Transition metal oxides are one of the most considered materials for high-performance photocatalysis. In this work, we investigate the effect of millisecond flash lamp annealing (FLA) of TiO2 on the degradation of methyl blue (MB) and methyl orange (MO). To reduce the energy consumption of the TiO2 deposition process, the layers were made using magnetron sputtering at room temperature, followed by millisecond FLA. By controlling the flash energy input, we can tune the phase formation of TiO2 films from pure anatase to mixed anatase/rutile phases. Scanning electron microscopy, positron annihilation spectroscopy, photoluminescence and X-ray diffraction studies show that the crystal size and film quality increase with increasing annealing temperature. Photocatalytic experiments demonstrate that FLA-treated TiO2 films are active in degrading both MB and MO. This makes them attractive not only for the production of green hydrogen, but also for the purification of water from medical contaminants.
- Published
- 2023
27. Group IV nanowires: fabrication, characterisation and applications
- Author
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(0000-0003-4627-9433) Khan, M. B., (0000-0002-2708-2718) Echresh, A., (0000-0003-1347-1365) Ghosh, S., Arora, H., (0000-0001-9938-2835) Chava, P., Jazavandi Ghamsari, S., Khan, M. M., Steuer, O., (0000-0002-4088-6032) Prucnal, S., (0000-0002-5200-6928) Hübner, R., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Helm, M., (0000-0001-6368-8728) Erbe, A., (0000-0002-3146-8031) Georgiev, Y., (0000-0003-4627-9433) Khan, M. B., (0000-0002-2708-2718) Echresh, A., (0000-0003-1347-1365) Ghosh, S., Arora, H., (0000-0001-9938-2835) Chava, P., Jazavandi Ghamsari, S., Khan, M. M., Steuer, O., (0000-0002-4088-6032) Prucnal, S., (0000-0002-5200-6928) Hübner, R., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Helm, M., (0000-0001-6368-8728) Erbe, A., and (0000-0002-3146-8031) Georgiev, Y.
- Published
- 2022
28. Group IV nanowires: a versatile toolbox for nano-and optoelectronic device
- Author
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(0000-0003-4627-9433) Khan, M. B., (0000-0002-2708-2718) Echresh, A., (0000-0003-1347-1365) Ghosh, S., Arora, H., (0000-0001-9938-2835) Chava, P., Jazavandi Ghamsari, S., Khan, M. M., Steuer, O., (0000-0002-4088-6032) Prucnal, S., (0000-0002-5200-6928) Hübner, R., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Helm, M., (0000-0001-6368-8728) Erbe, A., (0000-0002-3146-8031) Georgiev, Y., (0000-0003-4627-9433) Khan, M. B., (0000-0002-2708-2718) Echresh, A., (0000-0003-1347-1365) Ghosh, S., Arora, H., (0000-0001-9938-2835) Chava, P., Jazavandi Ghamsari, S., Khan, M. M., Steuer, O., (0000-0002-4088-6032) Prucnal, S., (0000-0002-5200-6928) Hübner, R., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4885-799X) Zhou, S., Helm, M., (0000-0001-6368-8728) Erbe, A., and (0000-0002-3146-8031) Georgiev, Y.
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- 2022
29. Axial p–n junction photodetectors based on single germanium nanowires
- Author
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(0000-0002-2708-2718) Echresh, A., (0000-0002-7958-4306) Shaikh, M. S., Arora, H., (0000-0001-6368-8728) Erbe, A., (0000-0002-8066-6392) Rebohle, L., (0000-0002-3146-8031) Georgiev, Y., (0000-0002-2708-2718) Echresh, A., (0000-0002-7958-4306) Shaikh, M. S., Arora, H., (0000-0001-6368-8728) Erbe, A., (0000-0002-8066-6392) Rebohle, L., and (0000-0002-3146-8031) Georgiev, Y.
- Abstract
Germanium (Ge) is considered as a promising candidate for designing near-infrared photodetectors. Ge has a bandgap of 0.67 eV, which induces a large absorption coefficient at near-infrared frequencies. Also, Ge has excellent compatibility of parallel processing with silicon technology [1,2]. Photodetectors based on Ge material have been fabricated with different structures such as metal-semiconductor-metal (MSM) and p−n junctions. On the other hand, the observation of high photoresponsivity in semiconductor nanowires with a high surface-to-volume ratio has attracted growing interest in using nanowires in photodetectors. So far, significant efforts have been made to fabricate single nanowire based photodetectors with different materials such as Si, Ge, and GaN to achieve miniaturized devices with high responsivity and short response time [3-5]. Hence, Ge nanowires are an excellent candidate to fabricated single nanowire based near-infrared photodetectors. In this work, we report on the fabrication and characterization of an axial p−n junction along Ge nanowires with different widths. First, through a resist mask created by electron beam lithography (EBL), the Ge layers were locally doped with phosphorus ions using ion beam implantation followed by rear-side flash lamp annealing. Then, the single Ge nanowire based photodetectors containing an axial p−n junction were fabricated using EBL and inductively coupled plasma reactive ion etching (ICP-RIE). The fabricated single Ge nanowire devices demonstrate the rectifying current-voltage characteristic of a p−n diode in dark conditions. Moreover, the photoresponse of the axial p−n junction based photodetectors was investigated under three different illumination lights of 637 nm, 785 nm, and 1550 nm wavelengths. It appears that fabricated photodetectors can be operated at zero bias and at room temperature under ambient conditions. A high responsivity of 3.7×102 AW-1, and detectivity of 1.9×1013 cmHz1/2W-1 were observed at ze
- Published
- 2022
30. A snapshot review on flash lamp annealing of semiconductor materials
- Author
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(0000-0002-8066-6392) Rebohle, L., (0000-0002-4088-6032) Prucnal, S., (0000-0003-3529-0207) Berencen, Y., Begeza, V., (0000-0002-4885-799X) Zhou, S., (0000-0002-8066-6392) Rebohle, L., (0000-0002-4088-6032) Prucnal, S., (0000-0003-3529-0207) Berencen, Y., Begeza, V., and (0000-0002-4885-799X) Zhou, S.
- Abstract
Flash lamp annealing (FLA) is a non-equilibrium annealing method on the sub-second time scale which excellently meets the requirements of thin film processing. FLA has already been used in microelectronics, mostly after ion implantation, to activate dopants, to recrystallize amorphous semiconductor layers, and to anneal out defects. Another field of application is the formation of silicide and germanide materials for contact fabrication. However, in the last twenty years, FLA has opened up new areas of application like thin films on glass, sensors, printed electronics, flexible electronics, energy materials etc. For two years, the Helmholtz Innovation Blitzlab aims to transfer this technology to industry and application-related research. After a short introduction, a brief overview of FLA is given, discussing the advantages and challenges of this technology. The main part displays various examples from literature and from our own research, in which FLA has been applied to semiconductors, namely to Si, Ge and GaN. In detail, the doping close or even above the solubility limit of dopants, the crystallization of Ge during FLA, the formation of NiGe for contacts, and p-type doping in GaN are addressed.
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- 2022
31. Sustainable electrode materials processing using flash lamp annealing
- Author
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Cherkouk, C., Folgner, C., Worbs, A., (0000-0002-5200-6928) Hübner, R., (0000-0002-4088-6032) Prucnal, S., Schumann, T., Krüger, S., (0000-0002-4885-799X) Zhou, S., (0000-0002-8066-6392) Rebohle, L., Cherkouk, C., Folgner, C., Worbs, A., (0000-0002-5200-6928) Hübner, R., (0000-0002-4088-6032) Prucnal, S., Schumann, T., Krüger, S., (0000-0002-4885-799X) Zhou, S., and (0000-0002-8066-6392) Rebohle, L.
- Abstract
Advanced energy materials and effective manufacturing facilities of battery cells production are key parameters to overcome the economic barrier to entry into the market. This poster shows an annealing technology using the millisecond range flash lamp annealing (FLA), which takes place without preheating and can be both a vacuum and vacuum-free method. This procedure at a pilot stage is characterized by significant savings in time, energy, resource and production costs enabling to enhance the sustainability of the battery production generally. It will review, as example, the advances that are obtained using FLA on new materials for high energy density thin film electrodes based on silicon. These new materials have the capability of realizing an excellent performance of the energy storage system, e.g. of lithium ion batteries and beyond, for vehicles and stationary applications. It will be demonstrated how it is possible to develop a silicon metal electrode (SiMe) with outstanding properties with a higher capacity than the standard of the day, compatible to many variants of lithium cells, solvents free, cost-effective and capable to be integrated on roll-to- roll processing.
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- 2022
32. Coherent coupling of metamaterial resonators with dipole transitions of boron acceptors in Si
- Author
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Meng, F., Han, F., Kentsch, U., (0000-0003-1309-6171) Pashkin, O., (0000-0002-3025-4883) Fowley, C., (0000-0002-8066-6392) Rebohle, L., Thomson, M. D., Suzuki, S., Asada, M., Roskos, H. G., Meng, F., Han, F., Kentsch, U., (0000-0003-1309-6171) Pashkin, O., (0000-0002-3025-4883) Fowley, C., (0000-0002-8066-6392) Rebohle, L., Thomson, M. D., Suzuki, S., Asada, M., and Roskos, H. G.
- Abstract
We investigate the coherent coupling of metamaterial resonators with hydrogen-like boron acceptors in Si at cryogenic temperatures. When the resonance frequency of the metamaterial, chosen to be in the range 7–9 THz, superimposes the transition frequency from the ground state of the acceptor to an excited state, Rabi splitting as large as 0.4 THz is observed. The coherent coupling shows a feature of cooperative interaction, where the Rabi splitting is proportional to the square root of the density of the acceptors. Our experiments may help to open a possible route for the investigation of quantum information processes employing strong coupling of dopants in cavities.
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- 2022
33. Fabrication of highly n-type-doped germanium nanowires and Ohmic contacts using ion implantation and flash lamp annealing
- Author
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(0000-0002-2708-2718) Echresh, A., (0000-0002-4088-6032) Prucnal, S., Li, Z., (0000-0002-5200-6928) Hübner, R., (0009-0003-0366-9690) Ganss, F., Steuer, O., Bärwolf, F., Jazavandi Ghamsari, S., Helm, M., (0000-0002-4885-799X) Zhou, S., (0000-0001-6368-8728) Erbe, A., (0000-0002-8066-6392) Rebohle, L., (0000-0002-3146-8031) Georgiev, Y., (0000-0002-2708-2718) Echresh, A., (0000-0002-4088-6032) Prucnal, S., Li, Z., (0000-0002-5200-6928) Hübner, R., (0009-0003-0366-9690) Ganss, F., Steuer, O., Bärwolf, F., Jazavandi Ghamsari, S., Helm, M., (0000-0002-4885-799X) Zhou, S., (0000-0001-6368-8728) Erbe, A., (0000-0002-8066-6392) Rebohle, L., and (0000-0002-3146-8031) Georgiev, Y.
- Abstract
Accurate control of doping and fabrication of metal contacts on n-type germanium nanowires (GeNWs) with low resistance and linear characteristics remain a major challenge in germanium-based nanoelectronics. Here, we present a combined approach to fabricate Ohmic contacts on n-type-doped GeNWs. Phosphorus (P) implantation followed by millisecond rear-side flash lamp annealing was used to produce highly n-type doped Ge with an electron concentration in the order of 10^19 − 10^20 cm^(−3). Electron beam lithography, inductively coupled plasma reactive ion etching, and nickel (Ni) deposition were used to fabricate GeNW-based devices with symmetric Hall bar configuration, which allows detailed electrical characterization of the NWs. Afterward, rear-side flash lamp annealing was applied to form Ni germanide at the Ni-GeNWs contacts to reduce the Schottky barrier height. The two-probe current-voltage measurements on n-type-doped GeNWs exhibit linear Ohmic behavior. Also, the size-dependent electrical measurements showed that carrier scattering near the NW surfaces and reduction of the effective NW cross-section dominate the charge transport in the GeNWs.
- Published
- 2022
34. On Curie temperature of B20-MnSi films
- Author
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Li, Z., Yuan, Y., Begeza, V., (0000-0002-8066-6392) Rebohle, L., Helm, M., Nielsch, K., (0000-0002-4088-6032) Prucnal, S., (0000-0002-4885-799X) Zhou, S., Li, Z., Yuan, Y., Begeza, V., (0000-0002-8066-6392) Rebohle, L., Helm, M., Nielsch, K., (0000-0002-4088-6032) Prucnal, S., and (0000-0002-4885-799X) Zhou, S.
- Abstract
B20-type MnSi is the prototype magnetic skyrmion material. Thin films of MnSi show a higher Curie temperature than their bulk counterpart. However, it is not yet clear what mechanism leads to the increase of the Curie temperature. In this work, we grow MnSi films on Si(100) and Si(111) substrates with a broad variation in their structures. By controlling the Mn thickness and annealing parameters, the pure MnSi phase of polycrystalline and textured nature as well as the mixed phase of MnSi and MnSi1.7 are obtained. Surprisingly, all these MnSi films show an increased Curie temperature of up to around 43 K. The Curie temperature is likely independent of the structural parameters within our accessibility including the film thickness above a threshold, strain, cell volume and the mixture with MnSi1.7. However, a pronounced phonon softening is observed for all samples, which can tentatively be attributed to slight Mn excess from stoichiometry, leading to the increased Curie temperature.
- Published
- 2022
35. Mid- and far-infrared localized surface plasmon resonances in chalcogen-hyperdoped silicon
- Author
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Wang, M., Yu, Y., Prucnal, S., Berencén, Y., Saif Shaikh, M., Rebohle, L., (0000-0003-4627-9433) Khan, M. B., Zviagin, V., Hübner, R., Pashkin, A., Erbe, A., Georgiev, Y. M., Grundmann, M., Helm, M., Kirchner, R., (0000-0002-4885-799X) Zhou, S., Wang, M., Yu, Y., Prucnal, S., Berencén, Y., Saif Shaikh, M., Rebohle, L., (0000-0003-4627-9433) Khan, M. B., Zviagin, V., Hübner, R., Pashkin, A., Erbe, A., Georgiev, Y. M., Grundmann, M., Helm, M., Kirchner, R., and (0000-0002-4885-799X) Zhou, S.
- Abstract
Plasmonic sensing in the infrared region employs the direct interaction of the vibrational fingerprints of molecules with the plasmonic resonances, creating surface-enhanced sensing platforms that are superior to traditional spectroscopy. However, the standard noble metals used for plasmonic resonances suffer from high radiative losses as well as fabrication challenges, such as tuning the spectral resonance positions into mid- to far-infrared regions, and the compatibility issue with the existing complementary metal–oxide-semiconductor (CMOS) manufacturing platform. Here, we demonstrate the occurrence of mid-infrared localized surface plasmon resonances (LSPR) in thin Si films hyperdoped with the known deep-level impurity tellurium. We show that the mid-infrared LSPR can be further enhanced and spectrally extended to the far-infrared range by fabricating two-dimensional arrays of micrometer-sized antennas in a Te-hyperdoped Si chip. Since Te-hyperdoped Si can also work as an infrared photodetector, we believe that our results will unlock the route toward the direct integration of plasmonic sensors with the on-chip CMOS platform, greatly advancing the possibility of mass manufacturing of high-performance plasmonic sensing systems.
- Published
- 2022
36. Blacklight sintering of ceramics
- Author
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Porz, L., Scherer, M., Huhn, D., Heine, L.-M., Britten, S., Rebohle, L., Neubert, M., Brown, M., Lascelles, P., Kitson, R., Rettenwander, D., Fulanovic, L., Bruder, E., Breckner, P., Isaia, D., Frömling, T., Rödel, J., Rheinheimer, W., Porz, L., Scherer, M., Huhn, D., Heine, L.-M., Britten, S., Rebohle, L., Neubert, M., Brown, M., Lascelles, P., Kitson, R., Rettenwander, D., Fulanovic, L., Bruder, E., Breckner, P., Isaia, D., Frömling, T., Rödel, J., and Rheinheimer, W.
- Abstract
For millennia, ceramics have been densified via sintering in a furnace, a time-consuming and energy-intensive process. The need to minimize environmental impact calls for new physical concepts beyond large kilns relying on thermal radiation and insulation. Here, we realize ultrarapid heating with intense blue and UV-light. Thermal management is quantified in experiment and finite element modelling and features a balance between absorbed and radiated energy. With photon energy above the band gap to optimize absorption, bulk ceramics are sintered within seconds and with outstanding efficiency (~2 kWh/kg) independent of batch size. Sintering on-the-spot with blacklight as a versatile and widely applicable power source is demonstrated on ceramics needed for energy storage and conversion and in electronic and structural applications foreshadowing economic scalability.
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- 2022
37. Self-driven Broadband Photodetector Based on MoSe2/FePS3 Van der Waals n-p Type-II Heterostructures
- Author
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(0000-0003-0168-665X) Duan, J., (0000-0001-9938-2835) Chava, P., (0000-0003-3060-4369) Ghorbani Asl, M., Lu, Y., (0000-0002-5831-7284) Erb, D., Hu, L., (0000-0002-2708-2718) Echresh, A., (0000-0002-8066-6392) Rebohle, L., (0000-0001-6368-8728) Erbe, A., (0000-0003-0074-7588) Krasheninnikov, A., Helm, M., Zeng, Y.-J., (0000-0002-4885-799X) Zhou, S., (0000-0002-4088-6032) Prucnal, S., (0000-0003-0168-665X) Duan, J., (0000-0001-9938-2835) Chava, P., (0000-0003-3060-4369) Ghorbani Asl, M., Lu, Y., (0000-0002-5831-7284) Erb, D., Hu, L., (0000-0002-2708-2718) Echresh, A., (0000-0002-8066-6392) Rebohle, L., (0000-0001-6368-8728) Erbe, A., (0000-0003-0074-7588) Krasheninnikov, A., Helm, M., Zeng, Y.-J., (0000-0002-4885-799X) Zhou, S., and (0000-0002-4088-6032) Prucnal, S.
- Abstract
2D van der Waals materials with broad-band optical absorption are promising candidates for next-generation UV-vis-NIR photodetectors. FePS3, one of the emerging antiferromagnetic van der Waals materials with a wide bandgap and p-type conductivity, has been reported as an excellent candidate for UV optoelectronics. However, a high sensitivity photodetector with a self-driven mode based on FePS3 has not yet been realized. Here, we report a high-performance and self-powered photodetector based on multilayer MoSe2/FePS3 type-II n-p heterojunction with a working range from 350 to 900 nm. The presented photodetector, operating at zero bias and at room temperature under ambient conditions, exhibits the maximum responsivity (Rmax) of 52 mA W-1 and external quantum efficiency (EQEmax) of 12% at 522 nm, which are better than the characteristics of its individual constituents and many other photodetectors made of 2D heterostructures. The high performance of MoSe2/FePS3 is attributed to the built-in electric field in the MoSe2/FePS3 n-p junction. Our approach provides a promising platform for broadband self-driven photodetector applications.
- Published
- 2022
38. Deposition of silicon oxide films on silicon using HelixJet – an atmospheric-pressure plasma jet process below 100 °C
- Author
-
(0000-0002-8066-6392) Rebohle, L., Quade, A., Schumann, T., Blaschke, D., Hübner, R., Heller, R., Foest, R., Schäfer, J., Skorupa, W., (0000-0002-8066-6392) Rebohle, L., Quade, A., Schumann, T., Blaschke, D., Hübner, R., Heller, R., Foest, R., Schäfer, J., and Skorupa, W.
- Abstract
Silicon oxide films are widely applied for their superior dielectric, chemical and mechanic properties as well as for their resistance against reactive chemicals. Simultaneously, there is an increasing number of applications which demand a low deposition temperature. In this work, we compare the material properties of SiOx layers deposited at ca. 70°C by atmospheric-pressure plasma jet deposition (PA) with those of SiO2 layers thermally grown or deposited by plasma-enhanced chemical vapour deposition. The films were deposited on silicon wafers and analysed using different analysis techniques. According to cross-sectional transmission electron microscopy and high-frequency capacitance-voltage measurements, the interface between the PA oxide and the Si substrate is smooth with no apparent defects and displays an electrically active interface defect density between 3.5-8.0×1012 cm-2 directly after deposition and below 2.0×1012 cm-2 after furnace annealing. Right after deposition, the PA oxide contains carbon and hydrogen in a concentration of several at%, and the SiO2 plasma polymer network comprises several active centres (residual charge, free radicals, non-saturated bonds). The most abundant configuration is the Si(-O)4 tetrahedron, followed by Si(-O)3 with similar intensity. This indicates that there are still dangling Si bonds or bonds terminated by hydroxyl or methyl groups. After furnace annealing, the formation of the SiO2 network is completed and the optical and electrical properties of the PA oxide converge to that of thermal oxide.
- Published
- 2022
39. Crystallization of semiconductor thin films by flash lamp annealing
- Author
-
Rebohle, L. and Rebohle, L.
- Abstract
Flash lamp annealing is a non-equilibrium annealing method on the sub-second time scale which excellently meets the requirements of thin film processing. It has already been used in microelectronics to activate dopants, to recrystallize amorphous semiconductor layers and to anneal out defects. However, in the last 20 years, flash lamp annealing has opened up new areas of application like thin films on glass, sensors, printed electronics, flexible electronics, batteries etc. Since two years, the Helmholtz Innovation blitzlab aims to transfer this technology to industry and application-related research. In this presentation, we give a short introduction to flash lamp annealing and discuss the pros and cons of this technology for thin film and semiconductor processing. In the main part we report about our activities in the field of Ge-based materials for electronic applications. This includes the n-type doping of Ge above the solubility level by ion implantation and flash lamp annealing, the doping of GeSn alloys, and the fabrication of NiGe for contact formation.
- Published
- 2022
40. Tutorial: Thermal processes in short time annealing: application examples and current trends
- Author
-
(0000-0002-8066-6392) Rebohle, L. and (0000-0002-8066-6392) Rebohle, L.
- Abstract
The tutorial gives an introduction to the technology of flash lamp annealing, discusses process-relevant issues like temperature profile, homogeneity and stress distribution, and presents a couple of examples in which thermal treatments of materials on short time scale is beneficial.
- Published
- 2022
41. Flash lamp annealing of GaN
- Author
-
Rebohle, L., Prucnal, S., Akhmadaliev, S., Kentsch, U., Rebohle, L., Prucnal, S., Akhmadaliev, S., and Kentsch, U.
- Abstract
The presentation gives a short overview of our recent activities to dope GaN with Mg by ion implantation and flash lamp annealing.
- Published
- 2022
42. Data publication: Coherent coupling of metamaterial resonators with dipole transitions of boron acceptors in Si
- Author
-
Meng, F., Han, F., Kentsch, U., (0000-0003-1309-6171) Pashkin, O., (0000-0002-3025-4883) Fowley, C., (0000-0002-8066-6392) Rebohle, L., Thomson, M. D., Suzuki, S., Asada, M., Roskos, H. G., Meng, F., Han, F., Kentsch, U., (0000-0003-1309-6171) Pashkin, O., (0000-0002-3025-4883) Fowley, C., (0000-0002-8066-6392) Rebohle, L., Thomson, M. D., Suzuki, S., Asada, M., and Roskos, H. G.
- Abstract
FTIR transmission spectra of the samples at various temperatures
- Published
- 2022
43. Microfluidic system for endocrine disrupting chemicals detection in waterish solution
- Author
-
Cherkouk, C., Rebohle, L., Howitz, S., and Skorupa, W.
- Published
- 2011
- Full Text
- View/download PDF
44. Bioconjugation of the estrogen receptor hER α to a quantum dot dye for a controlled immobilization on a SiO 2 surface
- Author
-
Cherkouk, C., Rebohle, L., and Skorupa, W.
- Published
- 2011
- Full Text
- View/download PDF
45. Deposition of silicon oxide films on silicon using HelixJet – an atmospheric-pressure plasma jet process below 100 °C
- Author
-
Rebohle, L., Quade, A., Schumann, T., Blaschke, D., Hübner, R., Heller, R., Foest, R., Schäfer, J., and Skorupa, W.
- Subjects
dielectric coating ,insulation ,thin films ,atmospheric plasma source ,corrosion protection ,silicon oxide - Abstract
Silicon oxide films are widely applied for their superior dielectric, chemical and mechanic properties as well as for their resistance against reactive chemicals. Simultaneously, there is an increasing number of applications which demand a low deposition temperature. In this work, we compare the material properties of SiOx layers deposited at ca. 70°C by atmospheric-pressure plasma jet deposition (PA) with those of SiO2 layers thermally grown or deposited by plasma-enhanced chemical vapour deposition. The films were deposited on silicon wafers and analysed using different analysis techniques. According to cross-sectional transmission electron microscopy and high-frequency capacitance-voltage measurements, the interface between the PA oxide and the Si substrate is smooth with no apparent defects and displays an electrically active interface defect density between 3.5-8.0×1012 cm-2 directly after deposition and below 2.0×1012 cm-2 after furnace annealing. Right after deposition, the PA oxide contains carbon and hydrogen in a concentration of several at%, and the SiO2 plasma polymer network comprises several active centres (residual charge, free radicals, non-saturated bonds). The most abundant configuration is the Si(-O)4 tetrahedron, followed by Si(-O)3 with similar intensity. This indicates that there are still dangling Si bonds or bonds terminated by hydroxyl or methyl groups. After furnace annealing, the formation of the SiO2 network is completed and the optical and electrical properties of the PA oxide converge to that of thermal oxide.
- Published
- 2022
46. On Curie Temperature of MnSi films
- Author
-
Li, Z., Yuan, Y., Begeza, V., Rebohle, L., Helm, M., Nielsch, K., Prucnal, S., and Zhou, S.
- Subjects
B20 MnSi ,Curie temperature ,Defects ,Strain - Abstract
B20-type MnSi is the prototype magnetic skyrmion material. Thin films of MnSi have a higher Curie temperature than its bulk counterpart. It is not yet clear by what and how the Curie temperature of MnSi thin films is affected. In this work, we grow MnSi films on Si(100) and Si(111) substrates with a broad variation in their structures. By controlling the Mn thickness and annealing parameters, the pure MnSi phase of polycrystalline and textured nature as well as the mixed phase of MnSi and MnSi1.7 are obtained. Surprisingly, all these MnSi films show an increased Curie temperature of up to around 43 K. However, the Curie temperature is independent of the structural parameters within our accessibility including the film thickness above a threshold, strain, cell volume and the mixture with MnSi1.7. Our work is drawing to revisit the origin of the Curie temperature of MnSi films.
- Published
- 2022
47. Spraying spin coating silanization at room temperature of a SiO 2 surface for silicon-based integrated light emitters
- Author
-
Cherkouk, C., Rebohle, L., Skorupa, W., Strache, T., Reuther, H., and Helm, M.
- Published
- 2009
- Full Text
- View/download PDF
48. Increased dephasing length in heavily doped GaAs
- Author
-
Duan, J., Wang, C., Vines, L., Rebohle, L., Helm, M., Zeng, Y.-J., Zhou, S., and Prucnal, S.
- Subjects
phase coherence length ,heavily doped GaAs ,ion implantation ,sub-second annealing ,plasmonic - Abstract
Ion implantation of S and Te followed by sub-second flash lamp annealing with peak temperature about 1100 oC is employed to obtain metallic n++-GaAs layers. The electron concentration in annealed GaAs is as high as 5×1019 cm-3, which is several times higher than the doping level achievable by alternative methods. We found that heavily doped n++-GaAs exhibits positive magnetoconductance in the temperature range of 3-80 K, which is attributed to the magnetic field suppressed weak localization. By fitting the magnetoconductance results with Hikami-Larkin-Nagaoka model, it is found that the phase coherence length increases with increasing carrier concentration at low temperature and is as large as 540 nm at 3 K. The temperature dependence of the phase coherence length follows〖 l〗_∅∝T^η (η~0.3), indicating defect-related scattering as the dominant dephasing mechanism. In addition, the high doping level in n-type GaAs provides the possibility to use GaAs as a plasmonic material for chemical sensors operating in the infrared range.
- Published
- 2021
49. Phase selection in Mn-Si alloys by fast solid-state reaction with enhanced skyrmion stability
- Author
-
Li, Z., Xie, Y., Yuan, Y., Ji, Y., Begeza, V., Cao, L., Hübner, R., Rebohle, L., Helm, M., Kornelius, N., Prucnal, S., and Zhou, S.
- Subjects
B20-MnSi ,Skyrmions ,Phase separation ,Flash lamp annealing - Abstract
B20-type transition-metal silicides or germanides are noncentrosymmetric materials hosting magnetic skyrmions, which are promising information carriers in spintronic devices. The prerequisite is the preparation of thin films on technology-relevant substrates with magnetic skyrmions stabilized at a broad temperature and magnetic-field working window. The canonical example is the B20-MnSi film grown on Si substrates. However, the as-yet unavoidable contamination with MnSi1.7 occurs due to the lower nucleation temperature of this phase. In this work, we report a simple and efficient method to overcome this problem and prepare single-phase MnSi films on Si substrates. It is based on the millisecond reaction between metallic Mn and Si using flash lamp annealing (FLA). By controlling the FLA energy density, we can grow single-phase MnSi or MnSi1.7 or their mixture at will. Compared with bulk MnSi the prepared MnSi films show an increased Curie temperature of up to 41 K. In particular, the magnetic skyrmions are stable over a much wider temperature and magnetic-field range than reported previously. Our results constitute a novel phase selection approach for alloys and can help enhance specific functional properties such as enhancing the stability of magnetic skyrmions.
- Published
- 2021
50. B20-MnSi films grown on Si(100) substrates with magnetic skyrmion signature
- Author
-
Li, Z., Yuan, Y., Hübner, R., Begeza, V., Rebohle, L., Helm, M., Nielsch, K., Prucnal, S., and Zhou, S.
- Subjects
B20-MnSi ,Skyrmions ,Flash-lamp annealing - Abstract
Magnetic skyrmions have been suggested as information carriers for future spintronic devices. As the first material with experimentally confirmed skyrmions, B20-type MnSi has the research focus for decades. Although B20-MnSi films have been successfully grown on Si(111) substrates, there is no report about B20-MnSi films on Si(100) substrates, which would be more preferred for practical applications. In this letter, we present the first preparation of B20-MnSi on Si(100) substrates. It is realized by sub-second solid-state reaction between Mn and Si via flash-lamp annealing at ambient pressure. The regrown layer shows an enhanced Curie temperature of 43 K compared with bulk B20-MnSi. The magnetic skyrmion signature is proved in our films by magnetic and transport measurements. The millisecond-range flash annealing provides a promising avenue for the fabrication of Si-based skyrmionic devices.
- Published
- 2021
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