The nucleation of the crystalline Ge phase in SiOxNy films implanted with Ge+ ions with the energy 55 keV to doses of 2.1 × 1015–1.7 × 1016 cm–2 and then annealed at a temperature of Ta = 800–1300°C under pressures of 1 bar and 1–12 kbar is studied. From analysis of the Raman spectra, it is concluded that amorphous Ge precipitates increase in size upon hydrostatic compression at a temperature of 1000°C. Raman scattering at optical phonons localized in Ge nanocrystals is observed only after annealing of the samples with the highest content of implanted atoms at a temperature of 1300°C. In the photoluminescence spectra, a peak is observed at the wavelength ∼730 nm. The peak is considered to be the manifestation of the quantum-confinement effect in nanocrystals ∼3 nm in size.