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Research article

Electronic structure, linear, nonlinear optical susceptibilities and birefringence of CuInX₂ (X = S, Se, Te) chalcopyrite-structure compounds

Ali Hussain Reshak¹ and S Auluck²

¹Institute of Physical Biology, South Bohemia University, Institute of System Biology and Ecology-Academy of Sciences, Nove Hrady 37333, Czech Republic

²Physics Department, Indian Institute of Technology, Kanpur (UP) 208016, India

author email corresponding author email

PMC Physics B 2008, 1:12doi:10.1186/1754-0429-1-12

Published:	19  May  2008

Abstract

The electronic structure, linear and nonlinear optical properties have been calculated for CuInX₂ (X = S, Se, Te) chalcopyrite-structure single crystals using the state-of-the-art full potential linear augmented plane wave (FP-LAPW) method. We present results for band structure, density of states, and imaginary part of the frequency-dependent linear and nonlinear optical susceptibilities. We find that these crystals are semiconductors with direct band gaps. We have calculated the birefringence of these crystals. The birefringence is negative for CuInS₂ and CuInSe₂ while it is positive for CuInTe₂ in agreement with the experimental data. Calculations are reported for the frequency-dependent complex second-order non-linear optical susceptibilities . The intra-band and inter-band contributions to the second harmonic generation increase when we replace S by Se and decrease when we replace Se by Te. We find that smaller energy band gap compounds have larger values of in agreement with the experimental data and previous theoretical calculations.

PACS Codes: 71.15.-m, 31.15.-p