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In this study, we introduce a noble method for the fabrication of highly crystalline hybrid TiO2-SiO2 thin films using laser irradiation under ambient conditions. Upon light absorption at the interface between TiO2 sol-gel film and Si wafer during the laser irradiation process, the TiO2 gel film coated on the Si wafer is transformed into anatase TiO2 film, and the surface of underlying Si wafer is oxidized to a 20.63 μm thick SiO2 film composed of nano-spheres with average diameter of 24.12 nm. The photocatalytic characteristics of the TiO2-SiO2 hybrid film on methylene blue and its discriminated morphologies are compared with those of a TiO2 film fabricated by conventional thermal annealing. The TiO2-SiO2 hybrid film shows enhanced super-hydrophilicity and superior photocatalytic characteristics, while thermally annealed 0.16 μm thick TiO2 films exhibit hydrophobic and low photocatalytic properties. The laser assisting process is promising for the fabrication of highly crystalline TiO2-SiO2 hybrid film with super-hydrophilic and photocatalytic characteristics.

Titanium nitride (TiNx) films were deposited on 304 stainless steel and silicon (100) wafers by ion source assisted magnetron sputtering. The effect of substrate bias voltage on the preparation and properties of TiNx films was investigated. The results show that as the substrate bias voltage increases from 0 V to −400 V, the deposition rate of TiNx film decreases significantly and the density increases, which can be attributed to the re-sputtering effect at high ion bombardment. The texture of TiNx films varies gradually from (111) to (200) with the increase of energy delivered into the growing film. The hardness of the film deposited under −200 V bias voltage reaches the maximum value, 12.9 GPa. Meanwhile, the toughness and corrosion resistance of the film reach a maximum at a bias voltage of −400 V. In conclusion, the density, hardness, toughness and corrosion resistance of TiNx films can be increased by changing the substrate bias voltage.

The metal oxide/graphene hybrid nanomaterials have been known as promising functional materials for advanced applications such as high capacitive electrode material of secondary batteries, and high sensitive material of high performance gas sensors. Here, morphology controlled vanadium dioxide (VO2) nanostructures were grown on Si wafer and exfoliated graphene by the vapor transport method using a horizontal furnace system. One-dimensional VO2 nanowires were grown on SiO2(300 nm)/Si substrate under 0.4 kPa condition. On the other hand, thick polycrystalline of VO2 platelets were grown on exfoliated graphene nanosheets under 0.4 kPa condition. In addition, polycrystalline VO2 platelets were only grown on exfoliated graphene nanosheets under 101 kPa (atmospheric pressure) condition. The growth of polycrystalline VO2 platelets on graphene nanosheets in atmospheric pressure condition is attributed to preferential growth on functional group of graphene surface such as carbonyl. The functional group is served as nucleation site of VO2 nanostructures.

We observe an improvement in the passivation quality of silicon nitride (SiNx) films formed on crystalline silicon wafers by catalytic chemical vapor deposition (Cat-CVD) under the storage at room temperature. Fluorescent light illumination enhances the improvement in the passivation quality of Cat-CVD SiNx films, although the passivation quality is also improved in the dark. We do not see any change of bonding configurations in the SiNx films by the storage at room temperature. Capacitance–voltage measurement reveals that an increase in positive charge density in the SiNx films improves their passivation quality. The improvement in the passivation quality of SiNx films is observed for SiNx films deposited at various substrate temperatures, and SiNx films deposited at higher temperature tends to show more significant improvement in the passivation quality.

International audience; This work reports on the deposition of strontium titanate (SrTiO3) thin films by on-axisradio-frequency magnetron sputtering. The on-axis sputter deposited SrTiO3 thin film showed drastic substrate etching due to the production of accelerated energetic negative oxygen ions, when applied power density on target is above a threshold value. The negative ion bombardment leads to the formation of surface micro-effects on the as-deposited SrTiO3 film or even complete removal of the substrate metallization. In order to understand the impact of negative ion bombardment and to limit these re-sputtering effects, the chemical composition and the thin film growth process were systematically studied as a function of deposition parameters. At high RF-power (~8 W/cm2), we observe surface etching at the center of the silicon wafer (~5.08 cm2). However, deposition of the thin film was possible in regions outside this etching zone. The key to achieve stoichiometric SrTiO3 thin film deposition at the axis-center was by controlling both deposition pressure and oxygen concentration, it minimized re-sputtering of the negative oxygen ions on the substrate surface. Polycrystalline growth of SrTiO3 thin films on platinized silicon substrates was optimized systematically and further extended to the deposition of polycrystalline SrTiO3 on MgO substrates.

Arsenic profiles in plasma doped silicon wafers were traced by scattering of H+ and H-2(+) ions at medium energies. Two wafers were doped with the same bias, gas pressure, total implanted dose and AsH3 concentration. After implantation, the wafers were submitted to industrial cleaning processes, resulting in the formation of a surface SiO2 layer, and one wafer was subjected to an additional thermal treatment. Scattering spectra of single and molecular ion beams with the same energy per nucleon and charge state differed only by the energy broadening due to the break-up of the molecule, allowing depth profiling by calculation of the dwell time before the backscattering collision. For the SiO2 layers of these samples a density reduction of, on average, 13% was observed, compared to thermally grown SiO2. In addition, the arsenic depth-profile determined were in close agreement with independent findings obtained by electron techniques.

In this study, aluminum oxide (Al2O3) thin films are deposited via spatial atomic layer deposition on p-type silicon wafer. Then, a post-deposition annealing is performed in oxygen to activate the field-effect and chemical passivation. The annealing temperature is varied from 300 °C to 750 °C, and its effect on the structural properties and carrier lifetime of Al2O3/Si is investigated. The results show that at the annealing temperature of 600 °C, the highest minority carrier lifetime obtained is 446.5 μs and maximum surface recombination rate is 22.4 cm/s. Annealing temperatures higher than 600 °C lead to deteriorate surface passivation due to insufficient hydrogen passivation and structural change from AlO4 to AlO6 that cause low oxide fixed charge. Photovoltaic performance is simulated and compared with experimental results. The simulation shows that the p-type passivated emitter and rear contact (PERC) solar cell with the Al2O3 single layer annealed at 600 °C can have open-circuit voltage (Voc) of 678 mV and conversion efficiency (η) of 21.96%, while the PERC solar cell with SiNx:H/Al2O3 doubled layer can achieve Voc of 679.7 mV and η of 22.03%, which is very close to the upper limit in the case of ideal rear passivation. The simulation is in a good agreement with the fabricated PERC solar cell showing Voc = 679.2 mV and η = 21.6%.

We investigated the hydrogen sensing capabilities of Pt Schottky diodes using nonpolar 10 1 ¯ 0 m-plane GaN (m-GaN) bulk crystals. The Pt Schottky diodes on m-GaN wafer exhibited the fast and reversible response upon exposure to various hydrogen concentrations. The maximum sensitivity of m-GaN diode sensor was measured as high as 2 × 104% at the forward bias of 0.1 V upon 4% hydrogen exposure. The Pt Schottky diodes on m-GaN sensors showed the selective sensing to hydrogen and negligible response to other gas species including CO, CH4, CO2, NO2, and NH3 at 25 °C. Our finding shows that Pt/m-GaN diode hold great potential for highly-sensitive hydrogen gas sensors due to the presence of nitrogen atoms having a much higher affinity to hydrogen than gallium atoms on nonpolar m-plane surface.

Perovskite-structured NaTaO3 films were epitaxially deposited on centimeter-sized SrTiO3(001) wafers by hydrothermal and solvothermal reactions to examine the surface science for an efficient photocatalytic water-splitting reaction. The addition of Ba cations in the starting solutions afforded Ba-doped NaTaO3 films. X-ray fluorescence holography was employed to investigate and confirm the heteroepitaxial relationship between the Ba-doped film and substrate.

Compliant substrates are one of the many promising lattice engineering approaches for hetero-epitaxy. There are many approaches to realize such compliant substrates. Silicon-on-insulator (SOI) wafer is a good option as it is readily available from industry. Previous studies on SOI using silicon thicker than 10 nm on insulator reported limited or no compliance. However, the effect of ultrathin silicon thickness ( 4 nm, the GaAs film is multi-crystalline. These films have been characterized by X-ray diffraction measurement, atomic force microscopy and transmission electron microscopy. These findings show the potential for SOI wafers as compliant substrates at ultrathin Si thicknesses.

We present a thorough study of the target-cleaning phase to estimate the healthiness of the target in a direct current (DC) magnetron sputtering deposition. The study is based on real-time plasma monitoring by means of optical emission spectroscopy during a traditional cleaning phase in an Ar atmosphere. In this work we demonstrate that intensities of Ar emission lines are sufficient indicators of the target cleanliness degree. To derive these results SiOxNy thin films were grown by reactive DC magnetron sputtering on silicon wafers for different deposition configurations of Ar, O2 and N2 fluxes. Refractive index of the resulting films is measured by in-situ spectroscopic-ellipsometry. A simple but robust estimator is used to determine the time when the target is ready to start deposition. Hence, this approach can be suited for an industrial environment since the time invested in the cleaning phase can be minimized avoiding the waste of material and time.

Germanium-on-insulator (GeOI) technology is a potential-alternative to the bulk-silicon based devices for radio-frequency (RF), and complementary metal oxide semiconductor applications at advanced technology nodes. A thin germanium channel is the key enabler of high mobility transistors and group-IV photonic devices. A prohibitive cost of GeOI wafers may discourage high volume manufacturing (HVM) despite promising performance. Here, we demonstrate epitaxial Gd 2 O 3 -Ge-Gd 2 O 3 thin film growth on Si(111) substrate in an HVM platform - RF magnetron sputter system, where, the first Gd 2 O 3 layer acts as buried-oxide (BOX) in the GeOI wafer. The second Gd 2 O 3 layer is used as a cap-layer to be removed later using wet etching. Both the Gd 2 O 3 layer is grown epitaxially at 750 ∘ C , while the germanium layer is grown at room temperature and crystallised later by solid phase epitaxy (SPE) technique. The entire growth is performed without vacuum-break, to enable high throughput and excellent interface control. To compare the quality of the heterostructure, this sputter based SPE is performed on: (1) in-situ sputter grown, versus (2) ex-situ molecular-beam-epitaxy (MBE) grown epitaxial Gd 2 O 3 BOX layer. The x-ray diffraction analysis confirms the formation of twin-free epitaxial Ge layer in the case of in-situ sputtered Gd 2 O 3 while twinned Ge layer is observed in the case of ex-situ MBE grown Gd 2 O 3 . The twinning of the Ge layer in the ex-situ process is further supported by transmission electron microscopy analysis. Finally, we have performed an experiment to study the impact of Gd 2 O 3 BOX layer thickness on the crystal quality of Ge layer and show that the Ge layer crystal quality remains intact irrespective of BOX layer thickness. Therefore, we have achieved twin free Ge epitaxy in RF magnetron sputter system, equivalent to in-situ All-MBE SPE process. Such a process enables low-cost GeOI wafer manufacturing for cost-effective RF transistors.

This paper studies the process of a diamond abrasive that polishes on a GaN workpiece surface by using molecular dynamics simulation. The workpiece has an array of asperities to imitate the surface roughness. The effects of motion parameters, motion pathways, abrasive sizes, and orientations on the stress, structure change, surface morphology, temperature, and the number of removed atoms are analyzed. Notably, the stick-slip behavior occurs when the abrasive crosses the asperity system at 5.0 A, causing the periodic marks of stress, structure change, and atomic strain on the surface. At 5.0 A depth, compared to the sliding motion, the rolling motion shows a higher rate of removing the workpiece atoms. Along the asperity, moving through the asperity peak leads to greater deformation and material removal than in the valley. Moreover, the bigger abrasive causes more severe deformations than the smaller one. At 5.0 A depth and a rough surface, changing the crystalline orientation does not induce adequate changes. This paper demonstrates the stick-slip behaviors through the asperity system model, the advantage of the rolling motion, the effects of the abrasive size, and the crystalline orientation on the surface morphology.

Because of their fascinating electrical/optoelectrical characteristics, two-dimensional molybdenum disulphide (MoS2) attracts much attention recently. However, it is still a challenge to fabricate wafer-scale MoS2 nanofilms of controlled thickness and high quality and that, limits their application. Here, a two-step thermal vulcanization method is proposed to fabricate wafer-scale MoS2 nanofilms with different thicknesses (3-10 layers). The synthesized MoS2 nanofilms have high uniformity and good quality. Furthermore, back gate field effect transistor (FET) arrays were fabricated based on these wafer-scale MoS2 nanofilms. The FET devices showed good electrical performance, mobility in the range of 0.44 ~ 0.96 cm2V−1s−1 and on/off ratio of ~103. Here, first-principle calculation was used to analyse the different types of defects observed in the tri-layer MoS2, the doping effects induced by the defects were also discussed. This work provides a reliable way to fabricate wafer-scale MoS2 nanofilms and give a detailed study of the electrical properties of multilayers MoS2 nanofilms paving the way for the manufacture of two-dimensional semiconductor materials.

Preparation of ultrathin alumina (Al2O3) films through Plasma-Enhanced Atomic Layer Deposition (PE-ALD) at low substrate temperature is discussed. The present work aims to investigate the physical mechanism of the PE-ALD deposition process and also the characteristics of the ultrathin alumina films on silicon 〈100〉 wafer deposited using the technique. The deposition was performed using trimethyl aluminum (Al (CH3)3) as the precursor and argon gas for purging. During deposition, the target temperature was kept constant at ~ 80, 100 and 150 °C and the pressure was ~ 1.3 × 10− 2 Pa. Two deposition cycles were tested, 400 and 800 cycles. As for understanding the process, the films deposited with and without oxygen plasma were compared. Various thin film characterization techniques, including Atomic Force Microscope (AFM), ellipsometry, Raman spectrometry measurement, X-ray diffraction (XRD), and indentation technique, were applied for investigating the film properties. A transmission electron microscope (TEM) equipped with high-angle annular dark-field imaging line scan modes and energy-dispersive X-ray spectroscopy acquisition was used for imaging thin film cross-sections. We found that the number of deposition cycles did not affect the substrate surface roughness as evidenced by AFM images. The mechanical property, the hardness of the film deposited with 800 cycles and plasma was the best. Raman spectroscopy measurements showed that a Al-O-Si phase exists when the films were deposited at 100 °C and 150 °C for 400 and 800 cycles under oxygen plasma atmosphere. While no Al-O-Si phase existed after the same number of ALD deposition cycle without plasma. Results from XRD measurements indicated that the films deposited at 100 °C and 150 °C for 400 and 800 cycles under oxygen plasma atmosphere has an Al-O structure. TEM images clearly displayed the interface between the thin films, SiO2 interface layers and Si substrates. As for the sample deposited at 80 °C, an Al2O3 film was hardly seen, but when increasing the deposition temperature to 100 °C and 150°, films started to build on top of the substrate. However, for all deposition conditions, TEM revealed that the amounts of carbon atoms in the reaction site remained relatively high.

Large-area, close-packed, monolayer colloidal crystals can be used as templates in the preparation of micro/nano films. This work proposes a hybrid method of spin coating and peeling–draining for the production of large-area, close-packed, monolayer colloidal crystals. First, large-area monolayer polystyrene (PS) colloidal crystals were obtained through spin coating. Then, the colloidal crystal film was peeled from surface of the intermediate spin-coated silicon wafer and transferred to another substrate using a customized experimental device. Oxygen plasma treatment was utilized to modify the wettability of the silicon wafer, increase the uniformity of spin coating, and reduce the adhesion work of peeling. The key process parameters, such as the duration of oxygen plasma treatment, spin speed, peeling speed, and drop rate of water surface, of the proposed method were thoroughly analyzed and optimized. Three-inch, wafer-scale, large-area, close-packed monolayer colloidal crystals were obtained using the proposed method, which combines the advantages of spin coating and gas-liquid interface self-assembly and offers a stable and controllable approach to the fabrication of monolayer PS colloidal crystals.

In the ultra large-scale integration process, as chemical mechanical polishing (CMP) is developing to higher precision, nano level planarity and sub-nano level roughness of wafer surfaces become key problems to be overcome. In this work, a theoretical model for local and total material removal was proposed based on the particle sliding trajectories and chemical-mechanical synergy, and the material removal distribution on wafer surface were analyzed. Furthermore, the chemical-mechanical mechanism was studied and synergy maps constructed. It is found that the passivation-wear and additive-synergistic effects dominate the material removal during CMP. This study establishes a correlation mechanism between the nano material removal and global uniformity of wafer surfaces, which provides theoretical and experimental framework for optimizing the slurry and the process parameters.

The use of proper surface preparation and cleaning methods for Si wafers prior to the deposition of passivation layers is essential to minimize surface recombination and realize high efficiencies (> 20%) in crystalline Si photovoltaic cells. In this work, the influence of wafer cleaning on the quality of surface passivation achievable for boron-doped emitters was investigated, including the use of different combinations of HCl, HF, HNO3, and ozonated deionized water (DIO3). These different surface preparations and cleaning sequences were performed on undiffused and boron diffused n-type Cz Si wafers, followed by the deposition of either silicon nitride (SiNx) or an aluminum oxide film capped with SiNx (Al2O3/SiNx stack). Additionally, both planar and anisotropically textured wafers were used. Injection-level dependent photoconductance measurements and calibrated photoluminescence imaging were performed on symmetrical boron diffused samples based on the different cleaning processes and passivation materials described above. Additionally, non-contact corona-Kelvin measurements were used to extract the total charge and interface defect density at the Si surfaces. We found that cleaning variations strongly influence carrier lifetime for SiNx passivated Si, but the effect is less pronounced in the case of Al2O3/SiNx stacks. It was further observed that DIO3-last treatment resulted in higher lifetimes for the SiNx stacks. Overall, it emerged that the (DIO3 + HF + HCl → HF → DIO3) clean is a promising and potentially low cost cleaning sequence for the photovoltaics industry.

In this work, we investigated the film growth and planarization properties of sequential polymerization initiated chemical vapor deposition method (SP-iCVD). Supersaturated concentration of monomer and small amount of initiator were introduced sequentially into chamber. The obtained film properties such as uniformity, polymer molecular weight and thermal stability were same or better than iCVD processed film. Additionally, good planarization of high aspect ratio (7:1) patterned wafer was demonstrated in SP-iCVD. The overburden from top of feature was within 20 nm and film thickness between isolated and dense feature areas was very uniform in this single-step process.

International audience; We present in this paper a method to measure the transmission spectra of optical filters composed of Complementary Metal-Oxide-Semiconductor (CMOS) compatible materials thin layers in order to be fully integrated on various types of CMOS image sensors (ambient light sensors, proximity detection, red green blue colour imaging, etc.). As the filters have to be deposited on top of a CMOS device, a good approach in order to evaluate with accuracy their response on chip is (i) to achieve the stacks on Siwafers (as it is the case for the CMOS sensor) (ii) then to perform a direct bonding of the structure on glass wafers (iii) in the end to remove the entire bulk silicon. In this way, we show the measured spectral responses of multilayer interference filters and can check particularly the agreement of the transmission peak with the theoretical calculations and its reproducibility wafer to wafer. It enables to optimize the filters optical designs and to demonstrate that the developed filters fulfill typical CMOS requirements of integration and reliability.

In this work, a nano-cavity patterned sapphire substrate (nc-PSS) is fabricated by using a self-formed meshed Pt thin film on a c-plane sapphire substrate. The light output power of a GaN-based light emitting diode on the nc-PSS is 45% greater than that of a control light emitting diode that was prepared on a flat c-plane sapphire substrate (f-SS) wafer. The GaN-based light emitting diode that was prepared on the nc-PSS exhibited much less drooping than a GaN-based light-emitting diode that was prepared on a commercial semi-sphere patterned sapphire substrate (r-PSS), mainly because the voids that formed at the cavities at the GaN/nc-PSS interface buffered the stress in the GaN epi-layers that was imposed by the sapphire substrate.

In this study, a SiOx:H/bi-SiNx:H/SiOx:H quadruple-layer anti-reflective coatings embedded by silicon nanocrystals (Si-NC ARCs) was deposited on an n-type monocrystalline silicon base solar cell with nanowire texturing, by means of plasma enhancing chemical vapor deposition. The average reflection of the Si-NC ARCs on the polished silicon wafer was 4.97% (300–1000 nm). The minority carrier lifetime of the silicon wafer with nanowire texturing was boosted by nearly 39 times after the Si-NC ARCs were deposited. Moreover, the Si-NC ARCs showed a significant luminescent down shifting effect (LDS), with strong absorbing at the blue-ultraviolet region, followed by re-emitting at the red-near-infrared region, thereby modifying the sunlight spectrum before they reached the solar cell, and thus obtaining a better spectrum response. After depositing the Si-NC ARCs without a significant increase in the cell cost, the external quantum efficiencies, short circuit current density and photo-conversion efficiency of the solar cell with nanowire texturing were significantly improved.

In this study, the effect of copper (Cu) oxide shell type and thickness on the intense pulsed light (IPL) sintering of Cu nanoparticle (NP) paste on silicon (Si) wafer was investigated. The Cu NPs were oxidized in a heating chamber at 100-300°C to demonstrate the IPL sintering characteristics according to the Cu oxide shell. Cu NPs oxidized at a temperature of 300°C were covered in a thick CuO shell, which can be well sintered on a Si wafer with high thermal conductivity by high energy of multiple IPL irradiation without re-oxidation. The oxidized Cu NPs were surface modified using silane dispersant to secure higher electrical conductivity. To observe a mechanism of the multiple IPL sintering process, in-situ resistance monitoring of Cu NPs electrode was conducted. Scanning electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy were performed to characterize the IPL sintered Cu NPs paste. The thickness of Cu oxide shell was measured using transmission electron microscopy. Also, zeta potential and sedimentation analysis were performed to analyze the dispersion of oxidized Cu NPs. Finally, the Cu NPs paste based electrode was fabricated on Si wafer using multiple IPL irradiation and it exhibited a low resistivity of 8.38 μΩ•cm.

Advanced semiconductor manufacturing technology has adopted an alkaline solution for copper (Cu) corrosion prevention instead of the traditional acidic solution in the post-cleaning process of copper chemical mechanical polishing. Low particle and residue removal efficiency has been an issue for this process. In this study, we investigated the formation of small residue defects and the cleaning mechanism to remove these defects. The results show it is insufficient to remove the small residue defects by using the traditional process parameter tuning. Adding some friction between the pad and the wafer surface allowed the defects to be effectively reduced.

Based on the current density (CD) experimental results reported in a literature for the copper through-silicon vias (TSVs) arising in the Cu/Ti/SiO 2 /Si wafer structure, the CD solutions were obtained through simulations in the ANSYS/LS-DYNA software linked with the “Johnson-Cook (J-C) Constitutive Model” module in this study. The numerical schemes are developed to obtain the following contents: (1) the determinations of the unknown coefficients in the J-C model by conducting the microtensile tests for per each component of the TSV structure; (2) the earliest element failure caused by the thermal strain/stress; (3) the critical stress and time at potential failure location modeled by the J-C model; and (4) the evaluations of strain energy density ( W failure ) required for element failures in the components and the effect of heat generation rate in per unit volume of Cu film on element failure. The numerical solutions predicted by the present models are confirmed to be very close to the reported experimental results, and thus validate the present predictions for temperature and time and the sequence of elements with the earliest failure in their component. The strain energy density ( W failure ) required to start the failure of an element is found to be dependent upon the TSV component material only, and is independent of the element's location in the same component. The heat generation in the Cu film is of importance to the order of the TSV components reaching its W failure , the time to have W failure increases along with the distance of the TSV component from the lateral surface of the Cu film. The smaller the distance is, the earlier the time that the W failure of an element is reached. An appropriate combination of a Ti film with a large thickness and SiO 2 film with a small thickness can reduce the maximum effective stress ( σ max ) and provide an efficient barrier for copper diffusion into the Si wafer substrate. This study can provide an efficient method for the design and failure protection of TSV structures.

The vapor phase pyrolysis deposition method was developed for the preparation of indium tin oxide (ITO) thin films with thicknesses ranging between 300 and 400 nm with the sheet resistance of 10–15 Ω/sq. and the transparency in the visible region of the spectrum over 80%. The layers were deposited on the (100) surface of the n-type silicon wafers with the charge carriers concentration of ~ 10 15 cm − 3 . The morphology of the ITO layers deposited on Si wafers with different surface morphologies, e.g., smooth (polished), rough (irregularly structured) and textured (by inversed pyramids) was investigated. The as-deposited ITO thin films consist of crystalline columns with the height of 300–400 nm and the width of 50–100 nm. Photovoltaic parameters of mono- and bifacial solar cells of Cu/ITO/SiO 2 /n–n + Si/Cu prepared on Si (100) wafers with different surface structures were studied and compared. A maximum efficiency of 15.8% was achieved on monofacial solar cell devices with the textured Si surface. Bifacial photovoltaic devices from 100 μm thick Si wafers with the smooth surface have demonstrated efficiencies of 13.0% at frontal illumination and 10% at rear illumination.

Thin films of guest-free type-II Si clathrate (Si136) were fabricated on Si(111) wafers in two steps: NaxSi136 thin-film formation by thermal decomposition of NaSi precursor films and Na removal from the NaxSi136 film by a heat treatment with iodine. Cross-sectional TEM observation and XRD and Raman measurements verified the formation of 1-μm-thick Si136 films on the Si wafer. Since the prepared films showed n-type conduction, pn junction devices were developed by a Si136/p-type Si structure. This device showed a photovoltaic (PV) response under white light illumination. The thin film formation and the PV response of Si136 indicated this Si allotrope to be the next-generation platform for semiconductor technology.

Pb(Mg 1/3 Nb 2/3 )O 3 –PbTiO 3 (PMN-PT) has attracted a great deal of attention for its use in capacitors, piezoelectric actuators, sensors, and optical devices in integrated circuits. For these applications, epitaxially grown PMN-PT thin films on Si wafers are required. This paper describes the first trial in fabricating epitaxially grown PMN-PT thin films on a LSCO/CeO 2 /YSZ buffered Si substrate using chemical solution deposition (CSD). High-quality buffer layers make the epitaxial growth of PMN-PT thin films possible, even by CSD. Despite very thin films that have thicknesses of 170 nm, the resulting PMN-PT thin films exhibit good electrical properties, such as a high dielectric constant of 1400 and well-defined P–E hysteresis loops.

This work discusses the effect of sample suspension in radio frequency plasma-enhanced chemical vapor deposition process on properties of the obtained overlays. Silicon nitride (SiN x ) overlays were deposited on flat silicon wafers and cylindrical fused silica optical fibers. The influence of the suspension height and fiber diameter on SiN x deposition rate is investigated. It has been found that thickness of the SiN x overlay significantly increases with suspension height, and the deposition rate depends on fiber dimensions. Moreover, the SiN x overlays were also deposited on long-period gratings (LPGs) induced in optical fiber. Measurements of the LPG spectral response combined with its numerical simulations allowed for a discussion on properties of the deposited overlay. The measurements have proven higher overlay deposition rate on the suspended fiber than on flat Si wafer placed on the electrode. Results of this work are essential for precise tuning of the functional properties of new generations of optical devices such as optical sensors, filters and resonators, which typically are based on optical fibers and require the overlays with well defined properties.

The Stoney equation has been a powerful tool for the thin film community to measure the residual stresses induced in a film through the measurement of curvature of a film–substrate system. Two of the main assumptions of the original Stoney equation are that the substrate is much thicker than the film and its material is isotropic in nature. However, in majority of the cases where the film stress is measured from the system curvature, Si wafers are used as substrates, which are anisotropic in nature. The anisotropic substrate problem was solved by Nix [1] for thick substrates. In this paper, a modified version of the Stoney equation is derived for configurations with thin anisotropic substrates, specifically for the cases of Si(001) and Si(111) wafers. The same methodology is then used to extend the Stoney formula to systems with bilayer films on thin substrates.

This work presents a custom, high-throughput combinatorial approach for the optimization of thermoelectric thin films consisting of materials with complex chemistry and structures (e.g., the layered misfit cobaltite, Ca 3 Fe x Co 4−x O 9 ). Combinatorial thin films with graded compositions are produced on 100 mm Si wafers from multiple target materials using pulsed laser deposition. Film thickness and composition are mapped as a function of wafer location. Crystal structures are determined using x–y mapping XRD analysis with specially designed algorithms for automated peak location and analysis. Thermoelectric properties, specifically the Seebeck coefficient and the electrical resistivity, are screened using a custom designed automated probe system. By combining the rapid synthesis of many compositions and structures simultaneously using combinatorial deposition and automated analytical tools capable of spatial mapping, trends in material performance are shown to be quickly obtained primarily due to the elimination of one-at-a-time synthesis and analysis. The possible approaches for such complex multivalent combinatorial optimization of thin films are identified and discussed. For the Ca 3 Fe x Co 4−x O 9 system presented, variations to the thermoelectric power factor are dominated by changes in the electrical resistivity. Enhancements to the Seebeck coefficient are observed due to the incorporation of Fe into the Ca 3 Fe x Co 4−x O 9 structure; however, this improvement is overshadowed by increases in the electrical resistivity due to variations in film thickness and the presence of secondary phases (Co 3 O 4 and Ca 2 Fe 2 O 5 ) which result from increasing Fe content and off-axis pulsed laser deposition.

In this study, a large-area (156 × 156 mm2) sub-wavelength antireflection structure has been fabricated on multi-crystalline Si substrates to reduce their surface reflectivity. A reactive ion etching (RIE) system was used to fabricate nanostructures on the multi-crystalline silicon surface. Reactive gases, comprised of chlorine (Cl2), sulfur hexafluoride (SF6) and oxygen (O2), were activated to fabricate nanoscale pyramids by radio frequency plasma. The pre-etching of poly-Si substrates using acidic and alkaline solutions was studied for creating the microstructures, which may affect the subsequent formation of nano-structures by RIE. Both the solar reflectance and the effective carrier lifetimes of multi-crystalline Si surface are measured to understand the effects of two pre-etching solutions. The pre-etching of silicon wafers using the acidic solution before RIE was found to improve the solar cell efficiency better than that using the alkaline solution. The absolute efficiency of solar cells with acidic pre-etching and RIE texturing can be improved by 0.64% over the traditional conventional cells.

The silicon heterojunction (SHJ) solar cell is one of the most promising candidates for the next-generation high-efficiency mainstream photovoltaic technology. It consists of a crystalline silicon wafer coated with a stack of functional thin-films on both sides. Conventionally, intrinsic and doped hydrogenated amorphous silicon (a-Si:H) is used as the passivation layer and emitter or back surface field (BSF), respectively. Hydrogenated microcrystalline silicon (μc-Si:H) is considered as a more advantageous alternative to the a-Si:H emitter and BSF layers due to μc-Si:H's higher electrical conductivity giving rise to lower series resistance. In this contribution, we use the catalytic doping process, so-called “Cat-doping”, to post-dope n-μc-Si:H thin-layers in such a way that the conductivity can be increased to higher levels than those achievable in as-grown n-μc-Si:H for the application in SHJ solar cells. We show that the conductivity of the μc-Si:H films notably increases after the Cat-doping. We also investigated the impact of Cat-doping on the conductivity of the different μc-Si:H and on lifetime.

In the present work we investigated the change of preferred crystalline orientation of indium oxide thin films prepared by ultrasonic spray technique on glass, single crystalline Si (400) and KCl single crystal substrates heated at 500 °C. The structural analysis suggests that films deposited on glass and Si wafer substrates are polycrystalline with a preferred grain orientation along the (222) plane. However, films deposited on KCl single crystal substrate, exhibit preferred (400) orientation. The films deposited on KCl substrates have larger grain size than the ones deposited on the other substrates. The electrical characterization indicated that films deposited on KCl substrates have lower resistivity of 0.8 × 10 − 3 Ω cm. While films prepared on glass substrates exhibit higher resistivity in the order of 33 Ω cm. This discrepancy is explained in terms of oxygen diffusion from the films towards the KCl substrate.

In this work we present SiOx films deposited in cost-effective laboratory scale three-dimensional printed atmospheric pressure chemical vapor deposition setup. As SiOx films are deposited at room temperature without complex vacuum systems, they can be a good candidate for the use in commercial c-Si solar cell production lines. The quality of the deposited films was investigated as to their integrity, conformity with various surfaces, and post-treatment resilience such as stability against etchants and annealing. Several applications of the SiOx film prepared with the atmospheric pressure chemical vapor deposition (APCVD) were discussed. In one application, the APCVD SiOx was utilized to effectively promote single-side texturing of Float Zone and Czochralski Si wafers by coating only one side with SiOx and subsequently annealing prior to texturing in an alkaline aqueous solution. Another application was to exploit the APCVD SiOx as a plating mask for silicon heterojunction solar cells. Two processing options prior to the oxide-film deposition were investigated: i) application of an Ag seed-layer, which promotes subsequent electroplating, and ii) printing of an organic grid, which, after stripping, creates openings in the SiOx that facilitate electroplating of the solar cell's electrode on the underlying transparent conducting oxide. In a different application, the APCVD SiOx films acted as protection against parasitic plating on the front side of passivated emitter and rear solar cells. The deposited films were characterized by ellipsometry, hemispherical reflectance measurements, scanning electron microscopy, energy dispersive X-ray spectroscopy and optical microscopy.

Polymethacrylimide (PMI) is a potential dielectric film for silicon-based microelectronics due to its good mechanical, thermal, and dielectric properties. However, the direct synthesis of an ultrathin PMI film on a silicon substrate remains challenging. In this paper, an in situ synthesis method has been developed to prepare ultrathin PMI (

High hydrogen content (CH) intrinsic amorphous silicon (a-Si:H) buffer layers were deposited on both sides of crystalline silicon wafers using plasma-enhanced chemical vapor deposition technique, which significantly improved surface passivation as well as conversion efficiency of the silicon heterojunction solar cells. Properties of the buffer layer and impact on the device performance were investigated. High resolution transmission electron microscope characterization shows that no obvious epitaxial growth occurred at the interface as long as a-Si:H buffer layer was introduced between c-Si and bulk intrinsic layer. Further study indicates that minority carrier lifetime of the device is related to hydrogen content of the buffer layer, reaching highest value up to 2050 ms at CH of 33%. These findings evidently confirmed that suppression of epitaxial growth and thus improved passivation were realized by using high-hydrogen-content a-Si:H buffer layer, based on which a high efficiency solar cell was prepared with large area.

Multi-layer graphene flakes with superior properties can be produced by chemical vapor deposition (CVD) on Ni substrates over large areas. We report a detailed investigation of lateral structures corresponding to correlated variations in Ni roughness and multilayer graphene thickness uniformity that may form under certain conditions over the wafer with large (mm to cm) feature size. Investigating these structures is important for understanding the interplay between carbon diffusion, segregation, metal grain formation and its role on graphene growth. In this study, we investigated such structures formed after CVD graphene growth on 200 nm Ni thin films on SiO2 (300 nm)/Si substrates by optical microscopy, atomic force microscopy, scanning electron microscopy and Raman microscopy. Our findings showed large-scale Voronoi-like structures featuring roughness variations in the Ni film correlated with the thickness distribution of the graphene multilayers. Ni recrystallization during the CVD process plays a pivotal role in forming these structures. Similar roughness-related structures do not form without a source of carbon (methane) present during the process, which shows that carbon diffusion/segregation and Ni recrystallization are mutually dependent.

In the chemical-mechanical planarization of oxide films, the polishing rate (the rate of material removal) decreases if the polishing pad is not regularly conditioned. Pad brushing, which removed polishing debris but did not otherwise alter the pad surface, was unable to restore the original polishing rate. On the other hand, pad conditioning, in which the pad surface was scraped off, restored the original polishing rate. The morphological state and the chemical modification state of the pad surface were evaluated as factors affecting the polishing rate. FTIR (Fourier-Transform infrared spectroscopy) analysis showed that some of the polyurethane molecules of the pad surface were hydrolyzed. The degree of pad modification at each position in the pad radial direction was quantified based on the FTIR results, and the degree of pad modification was compared with the actual polishing profile within a wafer. The profile based on chemical modification of the pad matched the actual polishing profile. It was shown that not only the morphological factors of the pad but also the chemical modification factors greatly affected the polishing rate.

We utilize indium tin oxide (ITO) as a material for direct bonding of Si wafers at low temperatures and without any pretreatment in order to create junctions of Si-ITO//ITO-Si. Transparent conductive oxides combine good conductivity with high optical transparency, rendering them ideal for joining III-V materials with Si based technology, e.g. to fabricate optoelectronic devices like light emitting diodes or solar cells. We found that bonded wafers did not display macroscopic defects and exhibit a bonding energy greater than 1 J/m2 determined by double cantilever beam test. This bonding strength is high enough to bear further front-of-line processing like backside grinding. The bonding interface was investigated by means of transmission electron microscopy to gain insight into the bonding mechanism. We observed that the bonding mechanism proceeds through grain growth of the ITO layers across the original bonding interface upon annealing above the crystallization temperature of ITO. To explore other factors which could influence the obtained wafer bonds, ITO layers were deposited on Si wafers and characterized before and after annealing by atomic force microscopy, scanning electron microscopy and X-Ray crystallography.

Silicon (Si) nanowires with twining or stacking faults are challenging their applications in microelectronic devices. It is of great value to explore the assembling principle of the crystal structure of Si nanowires. In this work, Si nanowires are grown by thermal annealing of nickel (Ni) coated Si wafers underneath an amorphous carbon layer. A systematically investigation is performed on the crystal structure of Si nanowires and the connected Ni catalyst particles using field emission scanning electron microscopy, high resolution transmission electron microscopy and selected area electron diffraction pattern. The results reveal that the defect-free Si nanowire has a highly crystalline Si core surrounded by the amorphous Si-oxide shell. Twinning and stacking faults are discovered locating near the Ni catalyst particles. The origin for the structural defects is explained by a structure-sensitive principle.

The present research focuses on the manufacturing of thin films using pure aluminum and aluminum-boron targets. The magnetron-sputtered films were produced at different discharge power levels on glass substrates and silicon wafers. Nanoindentation permitted characterizing the films’ hardness, elastic modulus, and adhesion strength, using the continuous stiffness measurement method and via a scratch test. In addition, this manuscript proposes a methodology to evaluate the film adhesion strength to the substrates upon a scratch test using a Berkovich tip. Nano-mechanical test results revealed that the film deposited from the aluminum-boron target had the larger elastic modulus, hardness, and adhesion strength than the pure aluminum films. Thus, the complementary characterization techniques allowed assessing how the material target, substrate type, and sputtering conditions influenced the mechanical behavior of the films.

The biocompatible thin film metallic glass (TFMGs) materials can be used to modify the substrate material due to their good corrosion resistance and adequate biocompatibility. In this work, five Fe–Zr–Nb TFMGs were fabricated on Si wafer and AISI420 stainless steel disk substrates using three pure targets co-sputtering system. The niobium target power was adjusted to grow TFMGs with different Nb contents ranging from 21.7 to 26.7 at%. Very fine and dense featureless microstructure was discovered for each Fe–Zr–Nb TFMG. The hardness, elastic modulus, H/E and H3/E2 ratios of Fe–Zr–Nb TFMG increased with increasing Nb content. Good adhesion property was revealed for each TFMG. The corrosion resistance of the bare AISI420 stainless steel disk was greatly improved by the deposited Fe–Zr–Nb TFMG. Very good biocompatibility and MG63 cell viability were also found for TFMGs implying their potential application as biomedical materials.

The potential of patterned nucleation growth (PNG) technique to control the wafer bowing of free-standing heteroepitaxial diamond films was investigated. The heteroepitaxial diamond (100) films were grown on an Ir(100) substrate via PNG technique with different patterns of nucleation regions (NRs), which were dot-arrays with 8 or 13 mm pitch aligned to < 100 > or < 110 > direction of the Ir(100) substrate. The wafer bows and the local stress distributions of the free-standing films were measured using a confocal micro-Raman spectrometer. For each NR pattern, the stress evolutions within the early stage of diamond growth were also studied together with a scanning electron microscopic observation of the coalescing diamond particles. These investigations revealed that the NR pattern, in terms of pitch and direction of dot-array, strongly affects the compressive stress on the nucleation side of the diamond film and dominantly contributes to the elastic deformation of the free-standing film. This indicates that the PNG technique with an appropriate NR pattern is a promising solution to fabricate free-standing heteroepitaxial diamond films with extremely small bows.

Lateral solid phase epitaxy (L-SPE) in non-doped or in-situ B-doped amorphous- (a-) SiGe deposited on SiO 2 patterned Si(100) wafers by in-situ postannealing in reduced pressure chemical vapor deposition system was investigated for possible heterojunction bipolar transistor (HBT) base link resistivity improvement. Using Si 2 H 6 as Si precursor gas, an epitaxial and amorphous layer was grown on the mask window and on the SiO 2 area, respectively. By inserting a-Si buffer underneath, the deposited a-SiGe surface became smoother. After the L-SPE process, an improved L-SPE length was observed due to suppressed random nucleation on SiO 2 . The L-SPE length increased with increasing postannealing time and saturated due to random poly-grain formation on the SiO 2 . At the same L-SPE time, increased L-SPE length was observed at higher temperature and at higher Ge concentration. With increasing B concentration in the a-SiGe, the L-SPE length firstly increased. However, after reaching 2 × 10 19 atom/cm 3 , the L-SPE length reduced again down to the undoped case. These results of L-SPE process might have potential to improve dynamic performance of SiGe HBT by reducing the base link resistivity by widening the monocrystalline region around bipolar window.

We present the design of infrared filters for multispectral imaging applications, based on square annular aperture arrays in a thin gold film. These structures function as band pass filters with large bandwidth and high transmission at resonance. A modal analysis based on the Finite Element Method (FEM) is performed to obtain quickly the features of this resonance. The center wavelength can be tuned in the 7–12 μm range while keeping constant the quality factor and maximum transmission by scaling all transverse dimensions of the apertures, which allows to obtain filters with different centering on the same substrate in a single fabrication step. Large area samples have been fabricated on a silicon wafer by electronic lithography. Spectrophotometric measurements are in rather good agreement with numerical predictions. In addition, angle resolved measurements show that the filters are quite tolerant to the incidence angle up to 30° for both polarizations which is consistent with our FEM simulations. Finally, a complete sensitivity analysis allows us to evaluate acceptable opto-geometric tolerances of fabrication and thus to improve reproducibility on large areas. The impact of fabrication defaults (rounded corners, aperture anisotropy, aperture edge roughness, sloping aperture edges) on the filtering performances is analyzed. The simulations of realistic structures allow to explain and reduce the differences between measured and simulated spectra.

Polycrystalline titanium thin films have been widely employed as interlayer between the substrate and different coatings in order to improve adhesion strength, corrosion resistance and wear performance, as well as to promote the growth of crystalline phases of the coating. The thickness of the Ti layer can be relevant on the behavior of the coatings, however very few studies have been carried out. In this work, the crystal structure of polycrystalline titanium films deposited with a vacuum arc discharge on monocrystalline silicon wafers (100) was studied and a dependence on the film thickness was found. The presence of the fcc phase of titanium was observed for the thinnest films with a critical thickness estimated in 300 nm, a much larger value than those reported for other deposition processes. For larger thicknesses, the films grew as α-titanium with a preferred orientation in the [100] direction. The obtained results agreed with a growth model based on the matching between the film and the substrate lattice. The characteristics of the films deposited in two steps, which had not been previously investigated, reinforced the suggested model.

5-inch diameter Bi 3.15 Nd 0.85 Ti 3 O 12 (BNT) ferroelectric thin films were prepared on Si wafers by a modified pulsed laser deposition method, in which two laser scanning rates and 6-inch diameter target were used. The investigation on the distribution of the film thickness reveals that the laser scanning technique used in conjunction with the large-diameter target can improve the uniformity of film thickness. Especially the reasonable setup of the laser scanning rate ablating the fringe area of the large target has a prominent effect on weakening the edge deviation of thickness distribution. Such phenomenon was fundamentally explained by the simulation results on the ablation tracks of the laser beam on target. Through optimizing the laser scanning rates, BNT thin film with uniform thickness was obtained on 5-inch diameter Si wafer and the maximum variation in film thickness was found to be less than ± 2.5%. The results of X-ray photoelectron spectroscopy and X-ray diffraction show that the prepared 5-inch BNT thin film has great uniformity in stoichiometry and crystallinity. In addition, the measurements of electrical properties indicated that the prepared BNT thin film exhibits good ferroelectric property and I – V characteristic.

Nanoscale wires of silicon oxide, among which some with embedded gold nanoparticles, are synthesized by a standard procedure involving the heating of a gold-coated silicon wafer at temperature higher than 1273 K. We report quantitative and systematic structural analyses of the silicon oxide nanowires with embedded gold nanoparticles performed by scanning electron microscopy, transmission electron microscopy, energy filtered transmission electron microscopy, X-ray diffraction, and optical transmittance measurements. For such pea-podded structures, the analyses allow us to correlate the diameter of the nanoparticles with the diameter of the nanowire in which they are embedded, and the diameter of the nanoparticles with their spacing. The results help in understanding the mechanism inducing the formation of such structures and indicate the coexistence of transport and instability processes during the growth stage.