Homoepitaxial Growth of Cubic GaN by Hydride Vapor Phase Epitaxy on Cubic GaN/GaAs Substrates Prepared with Gas Source Molecular Beam Epitaxy

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Abstract
Thick cubic GaN (c-GaN) layers were homoepitaxially grown on c-GaN/(100)GaAs by hydride vapor phase epitaxy (HVPE). The c-GaN crystals used as substrates in this work were prepared by gas source molecular beam epitaxy (GSMBE). When the growth temperature was too low (∼700° C) or too high (∼1000° C), hexagonal GaN (h-GaN) was included in the grown layer, but pure c-GaN was obtained at 900° C. The growth rate of c-GaN by HVPE in this work was about 1.6 µ m/h, which was 4–10 times higher than that of GSMBE or metalorganic vapor phase epitaxy (MOVPE), and an about 5 µ m thick c-GaN film was obtained by 3-h growth. The X-ray diffraction (XRD) patterns showed only the (200) and (400) c-GaN peaks but no h-GaN one. The cathodoluminescence (CL) spectra exhibited a strong peak at about 365 nm, which corresponds to the band edge emission. No emission due to deep levels was observed.