Contribution à l’étude des propriétés globales et locales des semi-conducteurs en vue d’application photovoltaïque et oscillateur paramétrique optique.

Abstract

This work concerns the ab-initio study of the optical properties of semiconductors which are interesting materials and potential candidates for many applications such as photovoltaic and optical parametric oscillator. We started by studying the structural properties of compounds; LiGaGe2Se6, LiGaGe2S6 and LiGaGe2Te6 Then, we were interested in the optical properties of these compounds. In order to gain an insight into the bonding and to characterize linear and nonlinear optical properties of three infrared LiGaGe2S6, LiGaGe2Se6 and LiGaGe2Te6 compounds, we performed a ab initio calculation based on density functional theory. The calculations determined lattice parameters, band gaps, dipole moments, and second harmonic components that commonly agreed well with the available experimental data. We show in this article, through a large body of calculations, the trends in the row of participating anions, S−Se−Te, enhances the polarization effect and the coordination structure distortions in the polyhedral groups forming the bonding pattern of the cell. This situation also affects both electronic and optical properties, making the compounds more propitious for device-based optical applications.