Synthesizing germanium nanocrystals in amorphous silicon oxide by rapid thermal annealing

Abstract

Abstract The Raman and photoluminescence (PL) characteristics of Ge nanocrystals embedded in amorphous SiO2 films synthesized by rapid thermal annealing were presented. The nanocrystal size δ was estimated on the basis of the phonon confinement model. The Raman results showed that, for samples annealed at different annealing temperatures, a transition from amorphous to nano-crystalline Ge occurred at annealing temperature higher than 700°C. δ was estimated to lie between 18 and 53 A. Two PL peaks at 1.8 and 2.2 eV were observed for Ge nanocrystals with δ= 18-53 Å. The PL results of the 2.2eV peak agreed with that published in the literature. The origin of this peak is still under investigation. A comparison of the PL peak with δ and the results of the forming-gas annealing experiments suggest that the 1.8 eV peak is possibly related to both the Ge nanocrystals and Ge related defects in the SiO2 network.