Quantum confinement effect on the electronic and optical features of InGaN-based solar cells with InGaN/GaN superlattices as the absorption layers

Abstract

The short period group III-V nitrides superlattices (SLs), have turned out contemporary in the technology of optoelectronics and solar cell applications. Our theoretical simulation is carried out by means of first-principles full potential linearized augmented plane waves (FP-LAPW) methodology within generalized gradient approximations (GGA) in conjunction with the modified Becke–Johnson (mBJ) potential. In this respect, a comprehensive study for the electronic structures and optical aspects of (InxGa1−xN)n/(GaN)n (001) zinc-blende superlattices (SLs) (x=0.5 and n=3–4), is carried out. Specifically, the electronic band structure calculations and their related features, like the absorption coefficient, reflectivity, refractive index and electron energy loss function spectra of these systems are computed over a wide photon energy scale up to 25eV. The effect of periodicity layer numbers and In composition (x=50%) on the band gaps of (InxGa1−xN)n/(GaN)n SLs is examined. The tailoring of the underlying energy band gap relies on the In content and the periodicity of the superlattices. All these ultrathin superlattices (n=3–4) possess a direct energy band gap. The InGaN layers have immense prominence in ascertaining the underlying energy gap of these superlattice because of the distinctive quantum confinement impact. Furthermore, the flexible energy gap of these ultrathin-period SLs leads to the alteration of the absorption coefficients and static refractive indices. It is viable to attain InGaN solar cells possessing high efficiencies since the energy gap covers all the spectrum optical regime. Predominantly, it is feasible to tune the optical characteristics of these short-period SLs and provide plausible results for the optoelectronic devices applications.