Kevin J. Linthicum

Pendeo-epitaxial growth of thin films of gallium nitride and related materials and their characterization

Abstract Monocrystalline GaN and Al x Ga 1− x N films have been grown via the pendeo-epitaxy (PE) 1 technique with and without Si 3 N 4 masks on GaN/AlN/6H-SiC(0xa00xa00xa01) and GaN(0xa00xa00xa01)/AlN(0xa00xa00xa01)/3C-SiC(1xa01xa01)/Si(1xa01xa01) substrates using organometallic vapor phase deposition. Scanning and transmission electron microscopies were used to evaluate the external microstructures and the distribution of dislocations, respectively. The dislocation densities in the PE grown films were reduced at least five orders of magnitude relative to the initial GaN seed layers. Tilting to 0.2° in the portion of the coalesced GaN epilayers grown over the silicon nitride masks was observed via X-ray diffraction. Neither tilting nor low angle boundaries were observed within areas of coalescence in the material grown on substrates without the masks. The strong, low-temperature PL band-edge peak at 3.45xa0eV with a FWHM of 17xa0meV was comparable to that observed in PE GaN films grown on 6H-SiC(0xa00xa00xa01). The band-edge in the GaN grown on AlN(0xa00xa00xa01)/SiC(1xa01xa01)Si(1xa01xa01) substrates was shifted to a lower energy by 10xa0meV, indicative of a greater tensile stress.