Interface effects on the thermoelectric properties of disordered semiconductors

Interface between metal and disordered semiconductor is commonly required to establish Ohmic contact. However, this requirement is not necessarily beneficial for thermoelectric applications, where heat transfer needs to be taken into account. This study systematically examines interface disorder effects using resistance network and kinetic Monte Carlo method, identifying a parameter space where all thermoelectric properties improve. Within the identified parameter space, the density of localized states varies, while the charge concentration keeps the same as in the bulk. It differs from Ohmic contact requirement, for which interface charge accumulation is beneficial. Thermopower increase is found as a result of filtering out the low-energy electrons by the interface layer. Simulation of the charge carrier dynamics reveals higher transport energies at the interfaces, implying local interface Seebeck coefficient greater than in the bulk. Conductivity increases because of better coupling between the extended electron states in metal and localized states in semiconductor, which is visualized as more uniform electric current at the interface. Relation of the model interface parameters to various effects, materials, and morphologies is discussed, along with relation to recent experiment by Petsagkourakis [], where the thermoelectric properties are shown to change not because of interface doping but rather owing to presence of a tunneling barrier. Published by the American Physical Society 2024