Influence of S vacancy and O doping in MoS2/GaN heterostructure on charge carrier dynamics: A time-domain ab initio study

Abstract

Van der Waals heterostructure MoS2/GaN is proposed as a promising candidate material for optoelectronic and photovoltaic applications, and we have studied the influence of S vacancy and O doping on charge carrier dynamics in MoS2/GaN, by means of ab initio nonadiabatic molecular dynamics simulations. It is found that these defects have negligible effect on charge carrier separation, and electron transfer is faster than hole transfer, owing to the stronger nonadiabatic coupling, originating from the more intermediate states and out-of-plane high frequency A1g mode. The presence of S vacancy in MoS2/GaN significantly accelerates the electron-hole recombination by introducing additional electronic states in band gap. It is notable that doping O atom in S vacancy in MoS2 layer induces stronger out-of-plane N atom vibration mode at 250 cm−1, resulting in shorter coherence between CBM and VBM states, which prolongs the carrier lifetime compared to that of the pristine MoS2/GaN.