Pendeo-epitaxial growth and characterization of GaN and related materials on (6H-SiC(0001) and Si(111) substrates

Discrete and coalesced monocrystalline GaN and AlxGa1-xN layers grown via P endeo-epitaxy (PE) [1] originated from side walls of GaN seed structures co ntaining SiNx top masks have been grown via organometallic vapor phase depo sition on GaN/AlN/6H-siC(0001) and GaN(0001)/AlN(0001)/3C-SiC(111)/Si(111) substrates. Scanning and transmission electron microscopies were used to ev aluate the external microstructures and the distribution of dislocations, r espectively. The dislocation densities in the PE grown films was reduced by at least five orders of magnitude relative to the initial GaN seed layers. Tilting in the coalesced GaN epilayers was observed via X-ray diffraction. A tilt of 0.2 degrees was confined to areas of mask overgrowth; however, n o tilting was observed in the material suspended above the SiC substrate. T he strong, low-temperature PL band-edge peak at 3.45 eV with a FWHM of 17 m eV was comparable to that observed in PE GaN films grown on 6H-SiC(0001). T he band-edge in the GaN grown on AlN(0001)/SiC(111)Si(111) substrates was s hifted to a lower energy by 10 meV, indicative of a greater tensile stress.