Optical properties of the low-energy Ge-implanted and annealed SiO2 films

Ultraviolet-visible light emissions from nanocrystalline (nc) Ge-embedded SiO2 films fabricated by ion implantation and rapid annealing techniques are studied as a function of different fabricating conditions (implanting dose and annealing temperature). The samples exhibit seven photoluminescence (PL) peaks peaked at 1.68, 1.75, 1.84, 1.93, 2.00, 2.70, and 3.10 eV. There are also two excitation bands in the PL excitation (PLE) spectra peaked at 4.90 and 5.19 eV. Raman spectra are employed to observe and understand structural variations in SiO2 matrix during the formation of nc-Ge and defects. Within the frame of the quantum confinement (QC) theory and Oswald ripening growth model, the origin and evolution of the seven PL peaks and two PLE bands are identified clearly demonstrated by the proposed energy-level and generated process diagrams. Our results indicate that both the implanting dose and annealing temperature play a dominant role in modulating the optical properties of the nc-Ge-embedded SiO2 films.