GaN grown on hydrogen plasma cleaned 6H-SiC substrates

Abstract

We report epitaxial GaN layers grown on 6H-SiC (0001) substrates. A two stage substrate preparation procedure is described which effectively removes oxygen from the SiC substrate surface without the need of elaborate high temperature processing. In the first step, dangling Si bonds on the substrate surface are hydrogen passivated using a HF dip before introduction into vacuum. Second, the substrate is treated with a hydrogen plasma reducing the amount of oxygen-carbon bonding to below the x-ray photoemission detection limit. Upon heating in the molecular beam epitaxy (MBE) growth chamber, the SiC substrates are observed to have a sharp (1×1) reconstruction with Kikuchi lines readily visible. GaN epilayers deposited on AlN buffer layers by plasma enhanced MBE show sharp x-ray diffraction and photoluminescence peaks.

Surface structures and growth kinetics of InGaN(0001) grown by molecular beam epitaxy

“…Some groups have reported a 2×2 reconstruction during growth [15], although we have found previously that this structure is due to the presence of arsenic atoms in the growth environment [16] (for growth using ammonia a different, intrinsic 2×2 structure occurs [17]). For the case of InGaN growth on (0001) face, we observe a bright √3×√3 reconstruction (in the absence of arsenic) at the growth temperature.…”

Initial Growth Prismatic Domains in Cyclotron Assisted MBE of GaN/SiC

“…The (0001) Si surface is treated using the classical way followed by a hydrogen plasma step in order to reduce the amount of oxygen-carbon bonds below the X-ray photoemission limit. The details of this procedure were reported by Lin et al [13]. Growth of the GaN layers was performed by an Electron Cyclotron Resonance plasma enhanced Molecular Beam Epitaxy, at a rate of 40 nm /h with a substrate temperature of 750 ¡C and a microwave power of 180 W. A nitrogen flow of 17 standard cubic centimeters per minute is used.…”

Optimized structural properties of wurtzite GaN on SiC(0001) grown by molecular beam epitaxy

“…[6], although there the FWHM of the x-ray data was close to that expected from the thickness of the films. We find that the FWHM of the symmetric peak is as low as 30 arcsecs for films grown at 700 C. This value is considerably smaller than that reported in some early GaN/SiC MBE growth studies [7,8], and is quite close to that reported in two recent studies [3,9]. Figure 2(b) shows FWHM data for the (11 4) and ( 024) asymmetric peaks from the same films obtained in double crystal rocking curves(ω scans).…”