Electronic structure of the InSb-CdTe-αSn interface: using CdTe as a barrier

The discovery and design of new inorganic interfaces with desirable properties for semiconductor, spintronic, and quantum devices offers a path to new device functionalities as well as improved performance of electronic circuits. We study the InSb-CdTe-αSn interface via density functional theory (DFT).  InSb is the backbone of Majorana devices for topological quantum computing and Sn is a superconductor that is utilized in Majorana devices. Though superconductivity is observed in the beta phase of Sn, α-Sn is explored here because the materials are lattice matched. CdTe is explored as a passivation layer and tunnel barrier material. The PBE+U method is used, with the Hubbard U parameters found via a machine-learned Bayesian optimization algorithm, which allowed the simulation of large interfaces. We discuss the results of DFT simulations considering the band offsets at the interfaces and the effects of varying the CdTe thickness. We show that once 16 layers of CdTe have been inserted this acts as an effective barrier.