Effect of p-d hybridization and structural distortion on the electronic properties of AgAlM2 (M = S, Se, Te) chalcopyrite semiconductors

TL;DR

This study uses ab-initio calculations to analyze how p-d hybridization and structural distortions influence the electronic properties of AgAlM2 chalcopyrite semiconductors, revealing significant effects on their band gaps.

Contribution

It provides a detailed first-principles analysis of structural and electronic properties, highlighting the impact of p-d hybridization and distortions on band gap variations.

Findings

Semiconductors are direct band gap materials with specific energies.

Anion displacement increases band gap by approximately 5-10%.

p-d hybridization decreases band gap by about 42-51%.

Abstract

We have carried out ab-initio calculation and study of structural and electronic properties of AgAlM2 (M = S, Se, Te) chalcopyrite semiconductors using Density Functional Theory (DFT) based self consistent Tight binding Linear Muffin Tin orbital (TB-LMTO) method. Calculated equlibrium values of lattice constants, anion displacement parameter (u), tetragonal distortion ({\eta} = c/2a) and bond lengths have good agreement with experimental values. Our study suggests these semiconductors to be direct band gap semiconductors with band gaps 1.98 eV, 1.59 eV and 1.36 eV respectively. These are in good agreement with experimental value within the limitation of local density approximation (LDA). Our explicit study of the effects of anion displacement and p-d hybridization show that band gap increases by 9.8%, 8.2% and 5.1% respectively for AgAlM2 (M = S, Se, Te) due to former effect and decreases by 51%, 47% and 42% respectively due to later effect.