Temperature-dependent electrical and optical studies on nonpolar a-plane GaN thin films with various Si-doping levels

Abstract

The electrical and optical properties of nonpolar a-plane GaN films with various silane flow rates were studied intensively utilizing temperature-dependent Hall-effect and photoluminescence measurements. The electron Hall mobility was found to change from increase to decrease while the silane flow beyond 16.06 nmol/min. It was inferred that the primary scattering mechanism of Si-doped GaN transferred from ionized impurity to thermal lattice vibration with the temperature over 450 K as more disordered lattice vibration was caused by Si doping. Meanwhile, the band-gap of nonpolar a-plane GaN film demonstrated a 32.56 meV narrowing owing to the Si-doping induced band-gap narrowing effect. Moreover, the basal stacking faults (BSFs) and Ga vacancy-related emission were evidently suppressed, and a decrease of 12.02% for BSFs density was achieved with Si-doping.