Conference Papers

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    Reduction of reflectance at c-silicon solar cell using nanotexturization
    (Institute of Electrical and Electronics Engineers Inc., 2014) Maity, S.; Kundu, A.; Das, S.; Chakraborty, P.
    Reduction in reflection losses of bare silicon surfaces has always attracted many researchers as it by far remains the most important criterion needed for achieving high efficiency solar cells. Anti-reflection coatings (ARC) of dielectrics help in balancing the refractive index mismatch between silicon and air. Although such ARCs help in reducing the reflection losses, they do not cause bending of light rays which is essential for efficient light trapping of the injected light into the cell. The technological leaps in the last few decades have lead to the possibility of nanotextured surfaces comprising of sub-wavelength structures in the optical domain. We report a simple and fast process for nanotexturing of the silicon surface may be achieved by creating silver nano-islands on the silicon surface and etching the exposed silicon surface. © 2014 IEEE.
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    Optoelectronic properties of graphene on silicon substrate: Effect of defects in graphene
    (SPIE spie@spie.org, 2015) Javvaji, B.; Ajmalghan, M.; Roy Mahapatra, D.; Rahman, M.R.; Hegde, G.M.
    Engineering of electronic energy band structure in graphene based nanostructures has several potential applications. Substrate induced bandgap opening in graphene results several optoelectronic properties due to the inter-band transitions. Various defects like structures, including Stone-Walls and higher-order defects are observed when a graphene sheet is exfoliated from graphite and in many other growth conditions. Existence of defect in graphene based nanostructures may cause changes in optoelectronic properties. Defect engineered graphene on silicon system are considered in this paper to study the tunability of optoelectronic properties. Graphene on silicon atomic system is equilibrated using molecular dynamics simulation scheme. Based on this study, we confirm the existence of a stable super-lattice. Density functional calculations are employed to determine the energy band structure for the super-lattice. Increase in the optical energy bandgap is observed with increasing of order of the complexity in the defect structure. Optical conductivity is computed as a function of incident electromagnetic energy which is also increasing with increase in the defect order. Tunability in optoelectronic properties will be useful in understanding graphene based design of photodetectors, photodiodes and tunnelling transistors. © 2015 SPIE.