Pendeo-epitaxial growth of gallium nitride on silicon substrates

Pendeo-epitaxy (PE)(1) from raised, [0001] oriented GaN stripes covered wit h silicon nitride masks has been employed for the growth of coalesced films of GaN(0001) with markedly reduced densities of line and planar defects on Si(111)-based substrates. Each substrate contained previously deposited 3C -SiC(111) and AlN(0001) transition layers and a GaN seed layer from which t he stripes were etched. The 3C-SiC transition layer eliminated chemical rea ctions between the Si and the NH3 and the Ca metal from the decomposition o f triethylgallium. The 3C-SiC and the GaN seed layers, each 0.5 mu m thick, were also used to minimize the cracking and warping of the GaN/SiC/silicon assembly caused primarily by the stresses generated on cooling due to the mismatches in the coefficients of thermal expansion. Tilting in the coalesc ed GaN epilayers of 0.2 degrees was confined to areas of lateral overgrowth over the masks; no tilting was observed in the material suspended above th e trenches. The strong, low-temperature PL band-edge peak at 3.456 eV with a FWHM of 17 meV was comparable to that observed in PE GaN films grown on A lN/6H-SiC(0001) substrates.