First-principles analysis for the modulation of energy band gap and optical characteristics in HgTe/CdTe superlattices

摘要

HgTe/CdTe superlattices (SLs), have emerged as unprecedented materials with tremendous functionalities, such as solar photocell devices. We carried out first-principles analyses in the framework of the full-potential linearized augmented plane wave (FP-LAPW) scheme to understand the impact of layer periodicity and strain on HgTe/CdTe superlattices. This technique allows us to describe the electronic and optical features of low dimensional systems, such as CdTe–HgTe heterojunctions. Alteration of the layer thickness and strain is imperative for tailoring the energy band gap of HgTe/CdTe superlattices. Thus, the CdTe and HgTe layers possess an appreciable influence on the induced forbidden gap of SLs because of their distinct quantum confinement characteristics. The electronic structures illustrate that the alteration in HgTe and CdTe layer thickness is pivotal for the overlap or non-overlap of the conduction bands and valence bands. Indeed, these systems can yield a semi-metallic or normal state with significant modification in the optical absorption of HgTe/CdTe SLs with respect to their bulk counterparts. Such SL systems have several advantageous features, involving their tailorable near band edge optical properties. Hence, it is feasible to optimize the requisite characteristics for electronic devices based on these SLs. This may enhance the development of HgTe/CdTe SLs in vast applications envisioned in infrared devices.