Electrical and optical properties of PbSe/PbTe heterostructures containing vacancies, doping, and alloys using first-principle calculations

Due to the increasing applications of heterostructures in recent years, in this work, a lead salt interface by PbSe and PbTe compounds (PbSe/PbTe) which are semiconductors with different bandgap energy and close lattice constant has been simulated. Using density functional theory (DFT) and general gradient approximations (GGA), the electronic and optical properties of the pure interface, vacancies, doped, and alloyed structures have been studied while transport properties have been calculated by DFT-non-equal green's function (DFT+ NEGF). The results of cohesive energy confirmed the structural stability of the heterostructures. Moreover, the electronic band structure results of interface structure for pure, vacancies, and doped (doping with O, S, Ge, Si, and Mg elements) showed no bandgap energy, while when it was alloyed with Mg a narrow indirect bandgap appeared. Moreover, peaks of absorption coefficient offered possible photocatalytic, infrared, and ultraviolet photodetector applicability. Furthermore, the absorption coefficient peaks are larger than the peaks of monolayer structures of the separated pure PbSe and PbTe which are reported in the other works. In addition, the results of quantum capacitance as a function of voltage have been reported which indicates a good potential candidate for transistor applications in the infrared region. The transport properties for the device which is made by Mg alloy interface as scatter area have been studied at different voltages.