Ge-implanted silicon dioxide is expected to be an attractive material for UV – blue light source with peaks at 290 and 390 nm in wavelength and the electroluminescence from Ge-implanted SiO₂ was reported at applied voltage of several hundred volts. For decreasing EL voltage down to ten volts or so, we have used a very thin SiO₂ layer on Si substrate. We implanted Ge negative ions into a thermally grown SiO₂ layer with a thickness of 50 nm at three times with energies of 50, 20 and 10 keV for the same sample. By this multi-energy implantation, almost uniform Ge concentration was obtained in a depth range from 5 to 35 nm. The average Ge-concentration is 3.0 at.% with Ge tails at different in 0.1 – 4 at.%. Samples were annealed twice in N₂ atmosphere and in decompressed air at 700^oC for 1 h. All of samples showed PL peak at 390 nm, but with almost the same intensity. By depositing ITO electrode in a comb shape on the sample surface, electroluminescence has been examined with alternative voltage. The EL emission was observed at AC voltage from 20 – 30 V. By applying DC voltage with negative volt to the ITO, we have obtained EL emission at DC 15 V at minimum from relatively high Ge concentration in the deep depth. The EL spectrum has a peak at 390 nm in wavelength as well as PL spectra. Details are presented at the conference.

Hiroshi Tsuji*, Kyoto University, Japan
Nobutoshi Arai, Sharp Corporation, Japan
Shohei Kinoshita, Kyoto University, Japan
Yasuhito Gotoh, Kyoto University, Japan
Junzo Ishikawa, Chubu University, Japan
Masatomi Harada, Sharp Coporation, Japan
Hiroshi Kotaki, Sharp Coporation, Japan

*presenting author