Thermal removal of oxide and carbide from 6H-SiC surfaces before molecular beam epitaxial growth of GaN


We have demonstrated growth of good quality GaN onto C-terminated 6H–SiC substrates by using a substrate-heating holder in a nitrogen–plasma molecular beam epitaxy (MBE) system. This substrate holder system can heat samples to the temperature region of 500–1500°C. Near-band-edge emissions have been observed from some of these epilayers, depending primarily on the substrate surface conditions. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) measurements show that the temperatures of 940–1245°C are necessary to thermally desorb the oxide and carbide from 6H–SiC substrates. Structural analysis by X-ray diffraction (XRD) and photoluminescence (PL) 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. The full-width at half-maximum (FWHM) values of the XRD and PL peaks are about 90 arc-second and 1.4 meV at 4.3 K for C-terminated 6H–SiC substrates, respectively. The results show that the deep-level recombination at 2.17 eV (yellow band) depends on the surface situation of the SiC substrate.


Physics, Astronomy, and Materials Science

Document Type




thermal removal, 6H–SiC surfaces, molecular beam epitaxial

Publication Date


Journal Title

Applied surface science