High efficiency infrared antireflection coatings (ARCs) for space optics

Simple ARC designs for germanium (Ge) optics useful in spaceborne electro-optical systems have been generated. It is seen that the designs which are non-quarterwave in nature are efficient in terms of spectral coverage and residual reflection loss. They have been realised experimentally and the resulting ARCs are found to have very good spectral and durability properties.

Antireflection properties of indium tin oxide (ITO) on silicon for photovoltaic applications

The short‐circuit current density (Jsc) of indium tin oxide (ITO/silicon solar cells has been shown both theoretically and experimentally to be a function of the thickness of the ion beam sputtered ITO layer. These results can be accounted for by computing the optical reflection from the ITO/silicon interface.

Theoretical Optimization of Metal Para-Normal Silicon Schottky-Barrier Solar-Cell

The theoretical optimization of the design parametersN A ,N D andW P has been done for efficient operation of Au-p-n Si solar cell including thermionic field emission, dependence of lifetime and mobility on impurity concentrations, dependence of absorption coefficient on wavelength, variation of barrier height and hence the optimum thickness ofp region with illumination. The optimized design parametersN D =5×1020 m−3,N A =3×1024 m−3 andW P =11.8 nm yield efficiencyη=17.1% (AM0) andη=19.6% (AM1). These are reduced to 14.9% and 17.1% respectively if the metal layer series resistance and transmittance with ZnS antireflection coating are included. A practical value ofW P =97.0 nm gives an efficiency of 12.2% (AM1).

Studies on thin film materials on acrylics for optical applications

Deposition of durable thin film coatings by vacuum evaporation on acrylic substrates for optical applications is a challenging job. Films crack upon deposition due to internal stresses and leads to performance degradation. In this investigation, we report the preparation and characterization of single and multi-layer films of TiO2, CeO2, Substance2 (E Merck, Germany), Al2O3, SiO2 and MgF2 by electron beam evaporation on both glass and PMMA substrates. Optical micrographs taken on single layer films deposited on PMMA substrates did not reveal any cracks. Cracks in films were observed on PMMA substrates when the substrate temperature exceeded 80degreesC. Antireflection coatings of 3 and 4 layers have been deposited and characterized. Antireflection coatings made on PMMA substrate using Substance2 (H2) and SiO2 combination showed very fine cracks when observed under microscope. Optical performance of the coatings has been explained with the help of optical micrographs.

Studies on the deposition and characterization of silicon oxide films for optical coating applications

Silicon oxide films were deposited by reactive evaporation of SiO. Parameters such as oxygen partial pressure and substrate temperature were varied to get variable and graded index films. Films with a refractive index in the range 1.718 to 1.465 at 550 nm have been successfully deposited. Films deposited using ionized oxygen has the refractive index 1.465 at 550 nm and good UV transmittance like bulk fused quartz. Preparation of graded index films was also investigated by changing the oxygen partial pressure during deposition. A two layer antireflection coating at 1064nm has been designed using both homogeneous and inhomogeneous films and studied their characteristics.