Growth of III-nitrides by RF-assisted molecular beam epitaxy

GaN, AlGaN, AIN were grown on (0001) Al2O3 substrates by MBE using a RF plasma source and employing an AlN buffer layer. The films were characterized by RHEED, AFM, and x-ray diffraction, and electrical properties were measured by Hall technique. RHEED observations indicate that the polarity of the films is likely predominantly N-face, although Ga-face inversion domains can be observed in some films by AFM. Symmetric x-ray rocking curve widths as low as 39 arcseconds are achieved for some layers, while asymmetric peaks show widths of 240-300 arcsec. Control of Si doping over a wide range is demonstrated, which is important for design of high power device structures. Gold Schottky barrier m-v-nf diodes were fabricated which achieve high reverse electric fields before edge breakdown.