Nitrogen centers in GaP produced by hot implantation |
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Authors: | T Shimada Y Shiraki KF Komatsubara |
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Institution: | Central Research Laboratory, Hitachi Ltd., Kokubunji, Tokyo, Japan |
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Abstract: | Backscattering yields of 1.5 MeV?He+ ions and low temperature photoluminescence (PL) spectra were measured in GaP crystals implanted with 200 keV?N+ ions as functions of ion-dose, temperature during implantation and annealing temperature after implantation. Backscattering results indicate that hot implantation at 500°C greatly reduces radiation damage. The PL intensities of NN lines become maximum in the sample implanted with N+ ions of 3 × 1014cm?2 at 500°C, and annealed at 1000°C for 1 hr with aluminum glass. The PL intensity is comparable to that of the nitrogen-doped sample during liquid phase epitaxy which is widely accepted as the best method of introducing nitrogen into GaP crystals. In the case of 500°C—hot implantation, the radiation damage produced during implantation is annealed out at 700 ~ 800°C and the implanted nitrogen substitutes for the phosphorous sites after annealing at 900 ~ 1000°C. Some kinds of defects or strains remain around the NN centers even in implanted samples with a maximum PL efficiency. These defects or strains don't seem to reduce the PL efficiency. In the case of room temperature implantation, PL efficiency decreases to one-hundredth or one-thousandth due to the formation of the non-crystalline state compared with hot implantation. |
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