Abstract
Ge/GeO2 core/shell nanoparticles embedded in an Al2O3 gate dielectrics matrix were fabricated. The core/shell nanoparticles consist of a single-crystal Ge core and a tiny GeO2 nanocrystallites shell. The high percentage of defects located at the shell surfaces and the grain boundaries between the Ge/GeO2 nanocrystals or disorderly arranged areas in the GeO2 shell induce a significant phonon localization effect, which leads to enhanced radiative recombination and thus it enhances the photoluminescence intensity. We believe that the findings presented here provide physical insight and offer useful guidelines to controllably modify the optical properties of indirect semiconductors through defect engineering.