Cathode and photo luminescence of silicon dioxide layer implanted with Ge negative ions at multi-energy

Ge- ions were implanted into SiO2 layer three times by changing the energies of 50, 20 and 10 keV to form Germanium nanoparticles at a relatively wide-depth region. Then, the samples were annealed at 600-900 deg. C for 1 h. Although Ge-nanoparticle formation was confirmed by cross-sectional TEM observation, XPS analysis showed about 30-60 % of the Ge atoms in SiO2 on average were oxidized. In cathode and Photo luminescence measurements, the emissions of around 400 nm in wavelength from the samples were observed. The position of cathode luminescence peak was independent of Ge fluence in the implantation, and temperature in the measurement. These results suggest that the luminescence mechanism is not due to quantum confinement effect of Ge nanoparticles, it is due to the oxygen defect center of oxidized germanium. The luminescence intensity changed dramatically with varying Ge fluence in the implantation