Investigation Of Elastic And Optical Properties Of Gallium Antimonide (GaSb) Using Density Functional Theories’’

Abstract

Gallium Antimonide (GaSb) is a semiconductor material with remarkable electronic, optical, mechanical, and thermodynamic properties, making it highly suitable for advanced applications such as infrared detectors, LEDs, laser diodes, and optoelectronic devices. In this study, the elastic and optical properties of GaSb were investigated using Density Functional Theory (DFT) within the Quantum ESPRESSO framework, with the lattice constant optimized to 6.2959 Å and a 6x6x6 k-point mesh for accurate sampling. The elastic constants obtained from stress-strain calculations C₁₁ = 620.44 kbar, C₁₂ = 359.44 kbar, and C₄₄ = 327.43 kbar—confirm GaSb’s mechanical stability, meeting Born and Huang’s criteria. The material also shows strong thermodynamic properties, with a bulk modulus of 44.64 GPa, Young’s modulus of 58.03 GPa, shear modulus of 22.64 GPa, Poisson’s ratio of 0.28, longitudinal sound velocity (Vp) of 3753.75 m/s, transverse sound velocity (VG) of 2064.80 m/s, and a Debye temperature of 220.5 K. These properties indicate GaSb’s robustness and vibrational stability. Electrically, GaSb is a direct bandgap semiconductor with an optical bandgap of 0.825 eV, high charge carrier mobility, and a clear density of states gap, making it ideal for infrared optoelectronic applications. Its optical properties, including the dielectric function, absorption characteristics, refractive index, and reflectivity, further demonstrate its potential for use in photodetectors, optical coatings, and energy harvesting technologies. Significant absorption peaks occur in the 1.5 eV to 3.5 eV range, while the imaginary part of the permittivity (ε₂) shows strong absorption between 2.5 eV and 4 eV, suggesting suitability for infrared photodetectors. The refractive index decreases with increasing photon energy, and the reflectivity is notably high in the ultraviolet and visible ranges, supporting its potential for optical coatings and filters. With strong absorption in the 3-5 eV range, GaSb is also promising for energy harvesting applications. Overall, GaSb’s combination of mechanical strength, high charge mobility, and diverse optical characteristics positions it as a promising material for a range of advanced photonic and optoelectronic devices. Further research, such as doping or heterostructure studies, could enhance its performance for specific applications, while experimental validation would further confirm its suitability for real-world use.