Fingerprints of native defects in monolayer PbTe.

Understanding the intricate interplay of defects and electron-electron interactions is crucial to exploiting the full potential of materials for practical applications. At the nanoscale, the combined effects are more pronounced due to quantum confinement and can have both positive and negative subtle effects on device performance. Herein, we report optoelectronic properties of pristine and disordered monolayer PbTe. We obtain the pristine electronic structure from first-principles calculations with the modified Becke-Johnson potential. We study the combined impact of random defects due to Te and Pb vacancies and material-specific electron-electron interactions on the electronic and optical properties of monolayer PbTe. We use a generalized energy-dependent Anderson-Hubbard Hamiltonian within a first-principles-based many-body typical medium method to self-consistently calculate the single-particle electronic structure. The absorption spectra, which also accounted for the effects of electron-hole interactions, are studied using valence electron energy-loss spectroscopy (VEELS) and they are obtained by solving the Bethe-Salpeter equation. Our results show an anomalous dependence on spin-orbit coupling for the pristine nanostructure and demonstrate that increased vacancy concentrations lead to, among other things, enhancement of the band gap, resonant shallow impurities, strong renormalization of the VEELS, and a systematic increase of the effective plasmon energy.