Effects of Cr Doping on the Physical Properties of Ga_1−<i>x</i>Cr_<i>x</i>As Alloys: An Ab Initio Study

This study employs first‐principles calculations to investigate the effects of varying Cr concentrations on the structural stability and electronic, magnetic, and optical properties of ternary Ga 1− x Cr x As alloys. The pseudopotential‐plane‐wave density functional theory calculations confirm the energetic stability of both pure GaAs and Ga 1− x Cr x As alloys, with stability decreasing as the Cr concentration increases. The alloy with 3.12% Cr exhibits the highest stability. Spin‐polarized band structures and density of states analyses reveal half‐metallic behavior at Cr concentrations of 3.12, 6.25, and 12.5%, transitioning to metallic behavior at 25%. The spin‐down bandgap decreases due to contributions from the Cr‐3 d state, accompanied by a noticeable bowing effect. The total magnetic moment remains constant at 3.00 μ B across all concentrations. Optically, the half‐metallic alloys exhibit the lowest static refractive index n (0), while the metallic Ga 0.75 Cr 0.25 As alloy shows the highest. Absorption and reflectivity analyses indicate that alloys with 3.12 and 6.25% Cr exhibit high absorption and moderate reflectivity in the visible and UV regions, outperforming pure GaAs. These findings underscore the potential of low‐Cr‐concentration Ga 1− x Cr x As alloys for applications in solar cells and optoelectronic devices.