To date, there is no ideal anti-reflection (AR) coating available on solar glass which can effectively transmit the incident light within the visible wavelength range. However, there is a need to develop multifunctional coating with superior anti-reflection properties and self-cleaning ability meant to be used for solar glass panels. In spite of self-cleaning ability of materials like TiO 2 and ZnO, these coatings on glass substrate have tendency to reduce light transmission due to their high refractive indices than glass. Thus, to infuse the anti-reflective property, a low refractive index, SiO 2 layer needs to be used in conjunction with TiO 2 and ZnO layers. In such case, the optimization of individual layer thickness is crucial to achieve maximum transmittance of the visible light. In the present study, we propose an omni-directional anti-reflection coating design for the visible spectral wavelength range of 400-700 nm, where the maximum intensity of light is converted into electrical energy. Herein, we employ the quarter wavelength criteria using SiO 2 , TiO 2 and ZnO to design the coating composed of single, double and triple layers. The thickness of individual layers was optimized for maximum light transmittance using essential Mcleod simulation software to produce destructive interference between reflected waves and constructive interference between transmitted waves.

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A new anti-reflection coating based on amorphous barium titanate (a-BTO) was developed using RF magnetron sputtering technique. Systematic studies on the structural and optical properties were carried on a-BTO thin films deposited on polished Si and textured Si substrates. In the visible range of solar spectrum, the refractive index was found to be 2.02-1.91 with high transmittance of greater than 85 %. Maximum reduction in the reflectance for a-BTO on polished Si and texture Si substrates was found to be 100 % (at 550 nm) to 85 % (at 400 nm), respectively. Further, improvement in cell efficiency of Si solar cell with a-BTO anti-reflection coating was found to increase from 9.3 % to 10 % with improvement in overall performance parameters such as short circuit density (J sc ), open circuit voltage (V oc ) and fill factor (FF).These results indicates that a-BTO thin film deposited using RF magnetron sputtering can be used as alternative anti-reflection coatings for Si based photovoltaic cells.

Ni films of thickness ranging from 150 to 250 nm were deposited by DC magnetron sputtering on to Si (100) substrates maintained at room temperature and followed by post-annealing at 300 and 500 °C for 30 min. Other set of Ni films were deposited on to Si (1 0 0) substrates held at annealing temperature of 300 and 500 °C for 30 min. Microstructural investigation by field emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM) revealed columnar morphology with voided boundaries for films deposited at room temperature and was retained after post-deposition annealing at higher temperatures. Nickel silicide formation with isosceles triangle diffusion front was confirmed by cross-sectional highresolution transmission electron microscopy (X-HRTEM) for post-annealed Ni films. Thin film deposited at high substrate temperatures having near-equiaxed structure found to be the best route to fabricate thin films without silicide formation.

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Thin films or a coating of any sort prior to its application into real world has to be studied for the dependence of process variables on their structural and functional properties. One such study based on the influence of substrate conditions viz. substrate-bias voltage and substrate temperature on the structural and morphological properties, could be of great interest as far as Ti thin films are concerned. From X-ray texture pole figure and electron microscopy analysis, it was found that substrate bias voltage strongly influence preferential orientation and morphology of Ti films grown on Si (100) substrate. Deposition at higher substrate temperature causes the film to react with Si forming silicides at the film/Si substrate interface. Ti film undergoes a microstructural transition from hexagonal plate-like to round-shaped grains as the substrate temperature was raised from 300 to 50 • C during film deposition.