High Gd Concentration GaGdN Grown at Low Temperatures |
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Authors: | Yi Kai Zhou Sung Woo Choi Shigeya Kimura Shuichi Emura Shigehiko Hasegawa Hajime Asahi |
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Affiliation: | (1) The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan |
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Abstract: | GaGdN layers were grown at temperatures below 300°C by radio-frequency plasma-assisted molecular beam epitaxy on sapphire substrates. GaGdN samples with high Gd concentration as high as 12.5% were obtained by lowering the growth temperature. X-ray diffraction results showed no obvious secondary phase, which means that the phase separation can be suppressed by the growth at low temperatures. All samples, including those grown at room temperature, showed ferromagnetic characteristics. Photoluminescence emission was observed, though spectra exhibit broad and sharp luminescence bands related to many kinds of defects. It is suggested that electrons coming from defects, especially, nitrogen vacancy, stabilize ferromagnetism, and that the carrier-induced ferromagnetism occurs in the low-temperature-growth GaGdN. |
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Keywords: | GaN-based diluted magnetic semiconductor GaGdN Ferromagnetism Photoluminescence Molecular beam epitaxy Defects |
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