Gallium diffusion through cubic GaN films grown on GaAs(100) at high-temperature using low-pressure MOVPE

Cubic GaN films were grown on GaAs(1 0 0) substrates by low-pressure metalorganic vapor-phase epitaxy at high temperature. We have found a nonlinear relation between GaN film thickness and growth timer and this nonlinearity becomes more obvious with increasing growth temperature. We assumed it was because of Ga diffusion through the GaN film, and developed a model which agrees well with the experimental results. These results raise questions concerning the role of Ga diffusion through the GaN film, which may affect the electrical and optical properties of the material. (C) 1998 Published by Elsevier Science B.V. All rights reserved.

Homoepitaxial growth and characterization of 4H-SiC epilayers by low-pressure hot-wall chemical vapor deposition

Horizontal air-cooled low-pressure hot-wall CVD (LP-HWCVD) system is developed to get high quality 4H-SiC epilayers. Homoepitaxial growth of 4H-SiC on off-oriented Si-face (0001) 4H-SiC substrates purchased from Cree is performed at a typical temperature of 1500 degrees C with a pressure of 40 Torr by using SiH4+C2H4+H-2 gas system. The surface morphologies and structural and optical properties of 4H-SiC epilayers are characterized with Nomarski optical microscope, atomic force microscopy (AFM), x-ray diffraction, Raman scattering, and low temperature photoluminescence (LTPL). The background doping of 32 pm-thick sample has been reduced to 2-5 x 10(15) cm(-3). The FWHM of the rocking curve is 9-16 arcsec. Intentional N-doped and B-doped 4H-SiC epilayers are obtained by in-situ doping of NH3 and B2H6, respectively. Schottky barrier diodes with reverse blocking voltage of over 1000 V are achieved preliminarily.