Lateral epitaxial growth techniques for gallium nitride thin films on 6H-silicon carbide(0001) substrates via metalorganic vapor phase epitaxy

Pendeo-epitaxy (PE) was developed as an alternative method to lateral epitaxial overgrowth (LEO) for the growth of GaN films with lower dislocation densities than that of conventionally grown films. In the PE technique, GaN is grown laterally from the sidewalls of etched stripes in previously deposited GaN seed layers grown on 6H-SiC(0001). The resulting GaN structure is suspended above the substrate and thereby avoids the formation of threading dislocations that arise from the lattice mismatch between the GAN film, buffer layer and substrate. The dislocation density in the laterally grown material is reduced by approximately five orders of magnitude. Uncoalesced and coalesced PE GaN structures have been successfully grown in this research.; The growth mechanism for GaN via lateral epitaxy (LE) is described using a model of interpenetrating hexagonal pyramids. In contrast to the moderate rates of lateral growth of this compound from seed stripes oriented along [112¯0], analogous growth from stripes oriented parallel to [11¯00] can have high lateral growth rates due to the competition between adjacent (101¯1) and (011¯1) facets. When appropriate growth conditions are employed, the competing facets yield to the fast growing metastable (112¯0) vertical facet. In the absence of competing facets, which occurs at the ends of the stripes, the morphology of the lateral growth reverts to the stable {lcub}11¯01{rcub} facets.; The formation of voids during the coalescence of GaN grown via lateral epitaxy is a common occurrence. These voids weaken the film and make it more susceptible to cracking. The interpenetrating hexagonal pyramid model is used to describe the growth mechanism leading to the formation of voids and their elimination. Experimental observations consistent with this model are presented. A novel method for the elimination of coalescence voids using an unconventional seed stripe orientation is also presented.