Theoretical analysis of the electronic, optical and thermal properties of lead strontium telluride alloys Pb_1−xSr_xTe (x = 0.0−1.0)

Abstract

We have simulated different physical properties of Pb_1−xSr_xTe semiconductors, using the Ab-initio full potential augmented plane wave (FP-LAPW) method. The two commonly used exchange potentials viz., PBE-GGA and WC-GGA are used along with the most recently developed modified Becke and Johnson (mBJ) potential to study the electronic and optical properties. In this study, we have observed an increase in band gap values as well as the lattice parameter with increasing the concentration of Sr atoms in Pb_1−xSr_xTe alloys while the bulk modulus and the refractive index have reverse effect. The microscopic origin of the band gap bowing is explained using the approach of Zunger and co-workers. At ambient conditions (p = 0, T = 0), the calculations indicate that Pb_1−xSr_xTe is a direct band gap semiconductor R–R with x = 0.125, 0.25, 0.375, 0.5, 0.625, 0.75 and 0.875. The refractive indices are also calculated using the FP-LAPW method and the models of Moss, Ravindra and the Herve–Vandame. The obtained results are in consistent with the previous available data. To study the thermal effects, the temperature effect on the lattice parameters, thermal expansions, heat capacities the quasi-harmonic Debye model is applied. The Debye temperature is determined from the non-equilibrium Gibbs function.

Keywords:

• DFT
• alloys
• electronic properties
• optical properties
• thermal properties

Acknowledgments

The authors (Khenata and Bin Omran) extend their sincere appreciations to the Deanship of Scientific Research at King Saud University for funding this Prolific Research Group (RGP-1438-88).