Abstract
Germanium nanoparticle in SiO2 is expected to be use to a charge trap, light emission source, etc. Ge nanoparticles can be formed in silicon dioxide films by negative ion implantation and heat treatment. However, under the heat treatment, these nanoparticles may be oxidized by residual oxygen in heat treatment atmosphere, or combination with oxygen in a silicone oxide film. The XPS analysis showed the oxidation of some implanted Ge atoms. Raman spectra were investigated to confirm the existence of Ge-Ge bonds in the nanoparticles. Ge negative ions were implanted into a thermally grown 100 nm-thick SiO2 film on Si substrate. After implantation, the samples were annealed at various temperatures. After annealing at temperature more than 600°C, each Raman spectra showed a peak around 270 - 300 cm^·1. These peaks corresponded to the Ge-Ge bonding depending on the size of Ge nanoparticles. The sample after annealing at 800°C showed strong peak at 300 cm^-1. The largest Ge nanoparticles are expected to form in the layer. However, there is no peak in the sample after annealing at 900°C.
