Preparation and photoluminescence properties of Ge nanocrystals embedded in SiO2 matrices with Ge–GeOx core–shell structure

The core/shell structure of Ge nanocrystals embedded in SiO2 matrix were prepared using the pulsed laser deposition (PLD) method with post-deposition annealing. X-ray diffractometry and Fullprof computer program revealed a bond length contraction of the Ge nanocrystals core in an annealed sample. This contraction was attributed to the compressive stress from the GeOx shell. The enhancement of photoluminescence was observed in the annealed sample, which is due to the Ge/O-related defects that existed in the interface between the Ge core and the GeOx shell.