Abstract In this study, we have investigated the effect of bi-axial, ϵab, and uni-axial, ϵc, strains on the optoelectronic properties of chalcopyrite semiconductor CuGaSe2 through first-principles full potential linearized augmented plane wave method. These materials have recently attracted much interest within the materials science community. The results are obtained in the framework of Density Functional Theory (DFT), using the Generalized Gradient Approximation based on the minimization of total energy, together with the modified Becke-Johnson exchange-correlation potential, as implemented in the WIEN2k code. Our results show that unstrained CuGaSe2 is a direct band gap semiconductor with a energy of 1.16 eV, thus improving the results of some previous DFT calculations, but still below the accepted experimental data. The incorporation of biaxial and uniaxial strain results in a monotonous decreasing behavior of the energy band gap when both ϵab and ϵc change between -8% and +8%, with unstrained value being, approximately, at the middle of the variation range. It is also found that strain causes modifications in the index of refraction of the material, with modifications of its static value that rank above 10% over the entire range of deformations considered.

中文翻译：

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晶格变形对 CuGaSe2 电子和光学性质的影响：从头计算

摘要 在本研究中，我们通过第一性原理全电位线性化增强平面波方法研究了双轴 ϵab 和单轴 ϵc 应变对黄铜矿半导体 CuGaSe2 光电特性的影响。这些材料最近引起了材料科学界的极大兴趣。结果是在密度泛函理论 (DFT) 的框架中获得的，使用基于总能量最小化的广义梯度近似，以及修正的 Becke-Johnson 交换相关势，如在 WIEN2k 代码中实现的。我们的结果表明，无应变的 CuGaSe2 是一种能量为 1.16 eV 的直接带隙半导体，从而改善了之前一些 DFT 计算的结果，但仍低于公认的实验数据。当 ϵab 和 ϵc 在 -8% 和 +8% 之间变化时，双轴和单轴应变的结合导致能带隙的单调下降行为，无应变值大约在变化范围的中间。还发现应变会导致材料折射率发生变化，其静态值的变化在所考虑的整个变形范围内均超过 10%。