LAUSR

Abstract To comprehend merits and demerits of Sc 0.25 Al 0.75 N alloys in WZ and ZB phases for optoelectronics and solar cell technology, we performed a comparative study of the elastic, electronic and optical properties of these alloys using first-principles methodology with density functional theory. The elastic constants (C ij , B, G, E, ν and B/G), longitudinal and shear wave velocities (v s , v l ) and Debye temperature θ D of ZB and WZ-Sc 0.25 Al 0.75 N alloys have been calculated for the first time. The calculated results show that ZB and WZ-Sc 0.25 Al 0.75 N alloys have the direct band gap and the ZB-Sc 0.25 Al 0.75 N alloy exhibit comparatively narrower energy gap than WZ. The density of states of W-Al 0.75 Sc 0.25  N and ZB-Sc 0.25 Al 0.75 N were analyzed. The peaks of imaginary dielectric function and absorption curves are at higher energy point for ZB-Sc 0.25 Al 0.75 N. The highest absorption of ZB-Sc 0.25 Al 0.75 N is 3.65 × 10 5 /cm at 14.26 eV, which is larger than wurtzite of 3.32 × 10 5 /cm at 11.22 eV. The average reflectivity of WZ-Sc 0.25 Al 0.75 N is lower than that of ZB-Sc 0.25 Al 0.75 N. Moreover wide energy gap of WZ-Sc 0.25 Al 0.75 N results in smaller values of the static refractive indices compared to ZB-Sc 0.25 Al 0.75 N. The comparison of the electronic and optical characteristics of the ZB-Sc 0.25 Al 0.75 N with those of WZ-Sc 0.25 Al 0.75 N endorses that ZB-Sc 0.25 Al 0.75 N can be a material of choice for optoelectronics and solar cell applications besides the WZ-Sc 0.25 Al 0.75 N.