Microstructure and Properties of SiC/SiC and SiC/III-V Nitride Thin Film Heterostructural Assemblies

Monocrystalline thin films, multilayered heterostructures and solid solutions containing selected combinations of SiC, A1N and GaN have been grown on 6H-SiC(0001) substrates by gas-source molecular beam epitaxy (GSMBE) or metallorganic vapor phase epitaxy (MOVPE). Polytype control of the deposition of 3C(β)-SiC(l11) and 6H-SiC(0001) was achieved via control of the substrate orientation, temperature and gas phase chemistry. Essentially atomically flat A1N films or island-like features were observed using on-axis or vicinal 6H-SiC substrates, respectively. The coalescence of the latter features at steps gave rise to incommensurate boundaries as a result of the misalignment of the Si/C bilayer steps with the Al/N bilayers in the growing film. The controlled growth of 3C-SiC films with low defect densities and atomically flat surfaces was achieved on the A1N films to form the first 6H-SiC/2H-A1N/3C-SiC multilayer heterostructures. Solid solutions of these two phases were also achieved. Monocrystalline GaN(OOOl) or AlxGa1-xN (0≤x≤1) thin films were also grown on the A1N(OOOl) films or directly on the same SiC surface at 1100°C, respectively, via metallorganic vapor phase epitaxy (MOVPE). The stages of growth of each of the above films, their microstructure and selected other properties will be described.