Photoluminescence (PL) and electroluminescence (EL) from Si~+- and Ge~+ -implanted SiO_2 layers thermally -grown on a Si substrate were studied. The PL spectra were recorded after annealing at temperature in the range of 400 deg C to 1200 deg C. Single-peak PL at 460 nm and double-peak PL at 420 and 385 nm due to Si~+ - implanted and Ge~+ - implanted oxide layers, respectively, reached a maximum following heat treatment at 500 deg C for 30 min. The EL spectra from the Ge-rich oxides after annealing at 1000 deg C correlated very well with the PL signal, and showed a linear dependence on the injection current. The EL effciency was estimated to be about 5x10~-4. High-resolution transmission electron microscopy (HRTEM) analysis showed that the formation of nanocrystals in the implanted oxide layers occurred at annealing temperatures in excess of 800 deg C. The observed light emission is attributable to the presence of ident to Si-Si ident to, ident to Si-Ge ident to and ident to Ge-Ge ident to centres in SiO_2.
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