GaN grown on two-step cleaned C-terminated 6H-SiC by molecular-beam epitaxy


A contaminant-free C-terminated 6H-SiC (0001) surface has been successfully prepared by a two-step method, which combines H2:He (1:1) plasma and heating at 940 °C for 100 min. On this surface, a high-quality GaN (0001) thin film is obtained by radio-frequency nitrogen-plasma- assisted molecular-beam epitaxy. Near-band-edge emissions have been observed from some of these epilayers, depending primarily on the substrate surface conditions. Auger electron spectroscopy measurements show that temperatures of 940-1245 °C are necessary to thermally desorb the oxide and carbide from 6H-SiC substrates. At 1040 °C for the C-face SiC and 1150 °C for the Si-face SiC, crystalline damage was reported in the form of graphite formation on the surface. This graphite was observed through x-ray photoelectron spectroscopy. Structural analysis by x-ray diffraction and photoluminescence indicates very good in-plane alignment of the GaN epilayers as the substrates are cleaned using H2:He (1:1) plasma at 940 °C for 100 min.


Physics, Astronomy, and Materials Science

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Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films