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Nonstoichiometric amorphous silicon carbide films as promising antireflection and protective coatings for germanium in IR spectral range
摘要： A technology for preparation of amorphous nonstoichiometric hydrogenated silicon carbide (a-SixC1-x:H) films using the PE-CVD method has been developed. Such films with refractive index n = 1.8–2.1 are suitable to obtain antireflection effect on germanium in the IR spectral region. Single- and two-sided antireflection coatings of Ge enabled to increase its optical transmission up to 65% and 96% in the maximum transmission, respectively. The obtained films have good mechanical properties (H > 12 GPa, E = 100 GPa). Presence of Si-C bonds in the a-SixC1-x:H films restricts their range of application to the spectral interval 2.5–10 μm. The prepared films are uniform in composition and have high adhesion to the substrate. Variation of deposition conditions makes it possible to obtain a-SixC1-x:H films having high hardness and Young's modulus. High deposition rate, optimal optical properties of the a-SixC1-x:H films and good combination of mechanical properties for the Ge/a-SixC1-x:H film structures make them to be promising for practical application as antireflection and protective coatings for germanium.
关键词： Germanium,Antireflection coatings,Elements of IR optics,Nonstoichiometric SiC films
更新于2025-09-19 17:15:36
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Optical optimization of a multi-layer wideband anti-reflection coating using porous MgF2 for sub-micron-thick CIGS solar cells
摘要： The optical losses associated with sub-micron absorbers in CIGS solar cells can be reduced by light management techniques. 3-D optical modelling was used to optimize light in-coupling and internal rear reflectance in a 750-nm thick CIGS reference solar cell. At the front side, an effective medium approximation (EMA) approach for describing optical properties of a MgF2-based anti-reflection coating (ARC) was applied. Taking reflectance as the cost function and sequential nonlinear programming as the optimization algorithm, an optimal porous-on-compact double-layer ARC was determined. This led to a wideband light in-coupling with a 6.8% improvement in the photo-current density (Jph) with respect to the reference solar cell without ARC. Considering the variation of the sunlight direction due to day and seasonal changes, different light incidence angles were investigated. The results indicate that in this case, our designed double-layer ARC outperforms the standard compact MgF2 single-layer ARC. By using the EMA approach, the amount of computational memory can be reduced by a factor of 30, shortening the simulation time from four days to one hour. At the rear side of the cell, a point-contacted MgF2/Al2O3 reflector, in combination with our proposed front ARC, enhances the Jph by 11.3% considering the same reference solar cell. Compared to a much thicker cell (1600-nm thick absorber) with no light management applied, our front-and-rear optical approaches more-than-compensate optical losses resulting from using thinner absorbers. This design is suitable for industrial uptake and practical to realize. Additionally, the approach of using EMA for double-layer ARC optimization is innovative with respect to other ARC approaches applicable to not only chalcopyrite photovoltaic technologies.
关键词： Thin films,Antireflection coatings,Light management,Photovoltaic
更新于2025-09-10 09:29:36