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Abstract: A method of Al2O3 deposition and subsequent post-deposition annealing (Al2O3-PDA) was proposed to passivate electrically active defects in Ge-rich SiGe-on-insulator (SGOI) substrates, which were fabricated using Ge condensation by dry oxidation. The effect of Al2O3-PDA on defect passivation was clarified by surface analysis and electrical evaluation. It was found that Al2O3-PDA could not only suppress the surface reaction during Al-PDA in our previous work [Yang H, Wang D, Nakashima H, Hirayama K, Kojima S, Ikeura S. Defect control by Al-deposition and the subsequent post-annealing for SiGe-on-insulator substrates with different Ge fractions. Thin Solid Films 2010; 518: 2342–5.], but could also effectively passivate p-type defects generated during Ge condensation. The concentration in the range of 1016–1018 cm−3 for defect-induced acceptors and holes in Ge-rich SGOI drastically decreased after Al2O3-PDA. As a result of defect passivation, the electrical characteristics of both back-gate p-channel and n-channel metal–oxide-semiconductor field-effect transistors fabricated on Ge-rich SGOI were greatly improved after Al2O3-PDA. [Copyright &y& Elsevier]

Abstract: The effects of activator concentration on the relaxation of the 1I6, 1D2, 1G4 and 3H4 levels of Tm3+ were investigated by the analysis of the fluorescence decay curves in Tm3+ and Tm3+/Tb3+ doped ZBLAN glasses. UV and blue upconversion luminescence bands around 362 and 450nm were observed by 655nm laser excitation in all the samples. The upconversion mechanism was attributed to excited state absorption (ESA) by analyzing the decay profiles and the intensity dependence. [Copyright &y& Elsevier]

Abstract: Ultraviolet and violet upconverted luminescence in high-concentrated (8.4at%) Er3+:YAG and low-concentrated (1at%) Er3+:YAP crystals has been investigated under blue laser excitation of the 4F7/2 multiplet. The upconversion mechanisms were studied in detail based on upconversion luminescence intensity dependence and decay curves. Upconversion luminescence was attributed to energy transfer processes in Er3+:YAG and excited state absorption processes in Er3+:YAP, respectively. [Copyright &y& Elsevier]

Abstract: The lifetimes of 3P0 and 1D2 levels of Pr3+ were measured in ZBLAN glasses of composition in mol% 53ZrF4–20BaF2–(4− x)LaF3–3AlF3–20NaF–xPrF3 (x =0.1, 0.5, 1, and 3) by resonant excitation. Energy transfer observed between Pr3+ ions was analyzed by means of the Inokuti–Hirayama theory. The non-exponential dependence of the 1D2 decay on Pr3+ concentration indicates that dipole–dipole interaction between Pr3+ is the main process. Orange-to-blue upconversion luminescence was observed and described by two-ion energy transfer mechanism. The temporal evolution of upconversion luminescence was characterized by rise and decay times related to the dopant concentration. [Copyright &y& Elsevier]

The postmetallization annealing (PMA) effect was investigated for a TiN-gate Ge metal-oxide-semiconductor capacitor with an ultrathin SiO2/GeO2 bilayer passivation. PMA at 450 °C led to the incorporation of nitrogen atoms into the gate stack. Consequently, the flat band voltage shifted from -0.79 to +0.23 V, resulting from a decrease in the dipole at the SiO2/GeO2 interface and the accompanying creation of a negative charge. The hysteresis decreased from 98 to 27 mV and the interface state density decreased from 6×1011 to 2.5×1011 cm-2 eV-1, as results of the nitrogen termination of defects at the SiO2/GeO2 interface and/or in the GeO2 interlayer. [ABSTRACT FROM AUTHOR]

Broadband antireflection (AR) coatings are essential elements for improving the photocurrent generation of photovoltaic modules or the enhancement of visibility in optical devices. In this paper, we report a hybrid nanostructured antireflection coating combination that is a clean and efficient method for fabricating a nanostructured antireflection coating (ARC). A multilayer thin-film was introduced between the ARC and substrate to solve the significant problem of preparing nanostructured ARCs on different substrates. In this way, we rebuilt a gradient refractive index structure and optimize the antireflective property by simply adjusting the moth-eye structure and multilayers. Subwavelength-structured cone arrays were directly patterned using a self-assembled single-layer polystyrene (PS) nanosphere array as an etching mask. Nanostructure coatings exhibited excellent broadband and wide-angle antireflective properties. The bottom-up preparation process and hybrid structural combination have the potential to significantly enhance the broadband and wide-angle antireflective properties for a number of optical systems that require high transparency, which is promising for reducing the manufacturing cost of nanostructured AR coatings. [ABSTRACT FROM AUTHOR]

We fabricated Ge n- and p-channel metal–oxide–semiconductor field-effect transistors (MOSFETs) with (100) surface orientation by the gate-last process. The source/drain junctions for n- and p-MOSFETs were fabricated by thermal diffusion of P and ion implantation of B, respectively, which indicated high on/off ratios. An ultrathin SiO2/GeO2 interlayer was used for fabricating the gate stack. The fabricated MOSFETs showed excellent electrical characteristics with a low interface state density. The peak electron and hole mobilities were 1097 and 376 cm2 V-1 s-1, respectively, despite the very thin GeO2 thickness (2 nm). These are 1.5–1.6 times higher than those of Si MOSFETs. [ABSTRACT FROM AUTHOR]

Al2O3 deposition and subsequent post-deposition annealing (Al2O3-PDA) is proposed as an effective method to passivate electrically active defects in Ge-rich SiGe-on-insulator (SGOI) substrates, which were fabricated using Ge condensation. We found that Al2O3-PDA could not only suppress the surface reaction during Al-PDA, but could also reduce the defect-induced hole concentration in Ge-rich SGOI, which was in the range of 1016–1018 cm-3 before Al2O3-PDA, by approximately one order of magnitude. Al2O3-PDA greatly improves the electrical characteristics of a back-gate metal–oxide–semiconductor field-effect transistor fabricated on Ge-rich SGOI. [ABSTRACT FROM AUTHOR]

Abstract: We experimentally report on the energy position, branching ratios, lifetimes and emission cross sections of the 1S0 level in Pr3+:ZBLAN glasses by two-step excitation process: 3H4 → 1D2 →4f5d. The calculated branching ratios and lifetimes of 1S0 by the standard as well as the modified Judd-Ofelt theories are compared with the measured ones. The results by the modified Judd-Ofelt theory, which more reasonably takes into account the effects of the configuration energies on the 5d perturbations to the 4f levels, have better agreements with the experimental results. The 1S0 luminescence by another two-step excitation process 3H4 → 3P0 →4f5d is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: The ultraviolet upconversion emission properties from Tm3+ ions doped ZBLAN glass upon 463nm laser excitation have been studied. Two ultraviolet emission bands, centered at 347nm for 1I6→3F4 Tm3+ transition and 362nm for 1D2→3H6 Tm3+ transition, have been observed. The responsible upconversion mechanisms were investigated by measuring time evolution spectra. [Copyright &y& Elsevier]

Abstract: Ge-MOS capacitors were fabricated by a novel method of ultra-thin SiO2/GeO2 bi-layer passivation (BLP) for Ge surface combined with the subsequent SiO2-depositions using magnetron sputtering. For the Ge-MOS capacitors fabricated by BLP with O2, to decrease oxygen content in the subsequent SiO2 deposition is helpful for improving interface quality. By optimizing process parameters of the Ge surface thermal cleaning, the BLP, and the subsequent SiO2 deposition, interface states density of 4×1011 cm−2 eV−1 at around mid-gap was achieved, which is approximately three times smaller than that of non-passavited Ge-MOS capacitors. On the contrary, for the Ge-MOS capacitors fabricated by BLP without O2, interface quality could be improved by an increase in oxygen contents during the subsequent SiO2 deposition, but the interface quality was worse compared with BLP with O2. [Copyright &y& Elsevier]

Abstract: Two kinds of HfSiO x /interlayers (ILs)/Ge gate stack structures with HfGeN- and GeO2-ILs were fabricated using electron cyclotron resonance (ECR) plasma sputtering and the subsequent post deposition annealing (PDA). It was found that HfGe was formed by the deposition of Hf metal on Ge and changed to HfGeN by N2 ECR-plasma irradiation, which was used as IL. Another IL was GeO2, which was grown by thermal oxidation at 500°C. For dielectrics with HfGeN-IL, PDA of 550°C resulted in effective oxide thickness (EOT) of 2.2nm, hysteresis of 0.1V, and interface state density (D it)=7×1012 cm−2 eV−1. For dielectrics with GeO2-IL, PDA of 500°C resulted in EOT of 2.8nm, hysteresis of 0.1V, and D it =1×1012 cm−2 eV−1. The structural change of HfSiO x /GeO2/Ge during the PDA was clarified by using X-ray photoelectron spectroscopy, and the gate stack formation for obtaining the good IL was discussed. [Copyright &y& Elsevier]

Abstract: The IR-to-blue and red upconverted fluorescence in Pr3+:Y2SiO5 has been observed at room temperature with a tunable OPO laser excitation. The upconversion mechanism is investigated by means of the power dependence and the decay profile of upconverted fluorescence. It appears that excited state absorption (ESA) process using 1G4 energy level as intermediate state is responsible for the upconversion fluorescence. [Copyright &y& Elsevier]

In this paper, we proposed a triple layer structure consisting of the bottom silver layer, thin silicon oxide space layer, and ultrathin semiconductor silicon film with nano hole array achieving three absorption peaks with narrow band. The absorption spectrum can be easily controlled by adjusting the structural parameters including the radius and period of the nano hole array, and the maximal absorption can reach 99.0% and the narrowest full width of half maximum can reach about 6.5 nm in theory. We also clarified the physical mechanism of the proposed structure in details by finite-difference time-domain simulation, in which the three narrow band perfect adsorption peaks can be attributed to electric dipole resonance, magnetic dipole resonance and plasmonic resonance respectively. At the same time, we used a low-cost nanosphere lithography method to fabricate the proposed nano hole array in large area. In experiment, the absorption peak of the proposed triple layer structure can reach up to 98.3% and the narrowest full width of half maximum can reach up to about 10.1 nm. The highest quality factor Q can reach up to 98.4. This work can open a new avenue for high-quality factor narrow band perfect absorption using ultrathin semiconductor film and benefit for many fields such as infrared sensors, plasmonic filters, and hyperspectral imaging.

We propose the use of thin Ag film deposition to remedy the degradation of near-infrared (NIR) absorption of black Si caused by high-temperature thermal annealing. A large amount of random and irregular Ag nanoparticles are formed on the microstructural surface of black Si after Ag film deposition, which compensates the degradation of NIR absorption of black Si caused by thermal annealing. The formation of Ag nanoparticles and their contributions to NIR absorption of black Si are discussed in detail.

High-efficiency surface plasmon enhanced 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane:C70 small molecular bulk heterojunction organic solar cells with a MoO3 anode buffer layer have been demonstrated. The optimized device based on thermal evaporated Ag nanoparticles (NPs) shows a power conversion efficiency of 5.42%, which is 17% higher than the reference device. The improvement is attributed to both the enhanced conductivity and increased absorption due to the near-field enhancement of the localized surface plasmon resonance of Ag NPs.