Enhancement of photoluminescence of Ge/GeO₂ core/shell nanoparticles

Ge/GeO₂ core/shell nanoparticles embedded in an Al ₂O₃ gate dielectrics matrix were fabricated. The core/shell nanoparticles consist of a single-crystal Ge core and a tiny GeO ₂ 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.