Deep-to-shallow level transition of Re and Nb dopants in monolayer MoS2 with dielectric environments

We investigate the effects of dielectric environments on the transition levels of Re and Nb dopants in monolayer MoS2 through density functional theory calculations. The inherently weakly screened Coulomb interaction in free-standing monolayer MoS2 makes the dopant electrons and holes strongly bound, and the Re and Nb impurities are found to produce deep levels. It is shown that when the monolayer MoS2 is placed near high permittivity dielectrics the screened Coulomb interaction induces carrier delocalization with generating shallow levels.