Effect of surface modification on the photoluminescent properties of γ-Ga2O3 nanocrystals

Abstract

Ga2O3 nanocrystals with compelling optical properties attract broad attention from the scientific and industrial community. However, the influence of surface modification on the photoluminescent properties of Ga2O3 NCs remains unexplored. Here, we report comparative investigations of the photoluminescent properties of oleylamine-capped and ligand-free γ-Ga2O3 nanocrystals. The removal of oleylamine ligand on the Ga2O3 nanocrystal surface via a post-synthesis reaction is accompanied by the accumulation of positive surface charges and a reduction of oxygen vacancies. The change of nanocrystal surface leads to an appreciable red shift of emission spectrum along with a substantial increase in photoluminescence lifetime. Modeling the photoluminescence decay dynamics of Ga2O3 nanocrystals indicate the change of photoluminescent property is correlated to the decrease of the number density of donors and donor Bohr radius resulting from the change of nanocrystal surface.