Effects of GaN passivation with SiO2 and SiNx studied by photoluminescence and surface potential electric force microscopy

Abstract

AbstractThe influence of passivation with SiO2 and SiNx on optical properties and surface band bending in unintentionally doped GaN has been studied by steady-state photoluminescence (PL) and surface potential electric force microscopy (SP-EFM). For both types of passivation we observed a significant increase of PL intensity in air ambient at room temperature. The measured surface potential was the same for control and passivated samples within the experimental error. The value of the surface band-bending was determined as 1.0±0.2 eV in all cases. We suggest that the strong enhancement of PL is caused by reduction of contribution of the surface states to recombination of photogenerated carriers after passivation.