The electronic and optical properties of InGaN-based solar cells alloys: First-principles investigations via mBJLDA approach

First-principles calculations of the electronic and optical properties of the bulk InxGa1-xN alloys are simulated within the framework of full-potential linearized augmented plane-wave (FP-LAPW) method. To this end, a sufficiently adequate approach, namely modified Becke-Johnson (mBJLDA) exchange correlation potential is employed for calculating the energy band gap and optical absorption of InGaN-based solar cells systems. The quantities such as the energy gap, density of states, imaginary part of dielectric function, refractive index and absorption coefficient are determined for the bulk InxGa1-xN alloys, in the composition range from x = 0 to x = 1. It is found that the indium composition robustly controls the variation of band gap. From the examination of the density of states and optical absorption of InxGa1-xN ternary alloys, the energy gaps are significantly reduced for largest In concentration. The computed band gaps vary nonlinearly with the composition x. It is also surmised that the significant variation in the band gaps elaborated via the experimental crystalline growth process, is originated by altering the In composition. Interestingly, it is worthwhile to perform InGaN solar cells alloys with improved efficiencies, because of their entire energy gap variation from 0.7 to 3.3 eV.