The properties of Ge nanocrystals formed by ion implantation of Ge+ ions into SiO2 films and subsequent annealing under hydrostatic pressure

The influence of hydrostatic pressure on ion synthesis of Ge nanocrystals in SiO2 matrix was studied. A retardation of Ge atom diffusion under conditions of high-pressure annealing was observed. It has been shown, that annealing at atmospheric pressure produces the unstressed Ge nanocrystals. In the case of high-pressure annealing, the hydrostatically stressed Ge nanocrystals have been formed. From the shift of the optical phonon frequency in Raman spectra the deformation of Ge nanocrystals is obtained. The E1, E1 + Δ1 Raman resonance shift observed from the nanocrystals corresponds to the basic state quantization energy of two-dimension exciton in M1 critical point of Ge band. It is shown that photoluminescence band of 520 nm was excited from the films containing the stressed Ge nanocrystals only