Conventional and pendeo-epitaxial growth of GaN(0001) thin films on Si(111) substrates
Single-crystal wurtzitic GaN(0 0 0 1) films have been grown via conventional methods on high-temperature AIN(0 0 0 1) buffer layers previously deposited on 3C-SiC(I I 1)/Si(I 1 1) substrates using metal organic vapor phase epitaxy (MOVPE). Formation of the 3C-SiC transition laver employed a carburization step and the subsequent deposition of epitaxial 3C-SiC(I 1 1) on the Si(1 1 1) surface using atmospheric pressure chemical vapor deposition (APCVD) for both processes. Similar films., except with significantly reduced dislocation densities. have been grown via pendeo-epitaxy (PE) from the (1 1 (2) over bar 0) sidewalls of silicon nitride masked. raised, rectangular, and [1 (1) over bar 0 0] oriented GaN stripes etched from films conventionally grown on similarly prepared, Si-based, multilayer substrates. The FWHM of the (0 0 0 2) X-ray diffraction peak of the conventionally grown GaN was 1443 arcsec. The FWHM of the photoluminescence (PL) spectra for the near band-edge emission on these films was 19 meV. Tilting in the coalesced PE-grown GaN epilayers of 0.2 degrees was confined to the areas of lateral overgrowth over the masks; no tilting was observed in the material suspended above the trenches. The strong, low-temperature PL band-edge peak at 3.456 eV with an FWHM of 17 meV in the PE films was comparable to that observed in PE GaN films grown on AlN/6H-SiC(0 0 0 1) substrates. (C) 2001 Elsevier Science B.V. All rights reserved.