Abstract
We implanted germanium negative ions into a 100-nm-thick SiO2 layer on Silicon substrate and have investigated about oxidation of implanted Ge atoms and cathode luminescence for the possibility of blue light emission. The ions were implanted into the same SiO2 layer with three times at different energies of 50, 20, and 10 keV (multi-energy implantation). The dose amounts were 1.4 x 10^16, 3.2 x 10^15 and 2.2 x 10^15 ions/cm2, respectively. Samples were annealed for 1 h at a temperature less than 900°C. The depth distribution and oxidation of implanted Ge atoms in the oxide were measured by XPS analysis with Ar etching. The depth profiles were well agreed with the cross-sectional TEM image. But some extent of Ge atoms diffused to the SiO2/Si interface at 900 °C. The chemical sifted spectra of Ge 2p3/2 showed about 60 % of the oxidation of Ge atom around the end of the range (EOR) even in the as-implanted sample. This oxidation was considered to be due to the excess oxygen atoms near EOR by forward of sputtered oxygen atoms from SiO2 layer. In cathode luminescence measurement, the Ge-implanted sample after annealing at 800°C showed strongest CL peak at 3.12 eV (397 nm in wavelength) in UV-blue region at room temperature. This means the Ge-implanted sample has a possibility for light emission in the UV-blue region.
