Emission from localized states in few-layer InSe (Part1: Theory)

The localized hole that binds to the acceptor (defect) in indium selenide (InSe) thin film has an important implication for the material’s optical properties since this localized hole in the valance band can recombine with the electron in the conduction band. To investigate this localized state, we build a mesoscopic model based on the GW computed quasiparticle energy. With this model, we find that the scattering processes between different quantized modes due to quantum confinement play a crucial role in forming the hole-acceptor bound pair. As a result, the charge density of the hole bound state is highly inhomogeneous and strongly depends on the acceptor position in the out-of-plane direction. This leads to interesting electric-field dependence of the bound state energy due to the inversion symmetry breaking.