Relativistic effects on the electronic and optical characteristics of Cd1-xHgxTe alloys-based solar cell materials

The relativistic effects and compositional dependence on the electronic and optical properties of Cd1-xHgxTe alloys are reported by employing ab-initio self-consistent calculations based on full potential linear augmented plane-wave method (FP-LAPW) within the generalized gradient approximation (GGA). The electronic and optical characteristics are explored using the GGA combined with the modified Becke-Johnson (mBJ) potential, and spin-orbit coupling (SOC) is also incorporated. The mBJ-GGA + SOC scheme reveals the ability to alter the energy gap for Cd1-xHgxTe alloys by manipulating the Hg composition. The alloy undergoes a change from semimetal to semiconducting behavior. An accurate knowledge of the electronic band parameters is crucial in these mixed ternary alloys. For Hg-rich content of 75%, a band gap was found at around 0.15 eV. The direct energy band gap and significant absorption between the infrared and ultraviolet spans would suggest prominent optical activity in these promising systems.