Metalorganic chemical vapor phase epitaxy and structural properties of Ga 1-x P x N on GaN/Si(111) substrates

GaPN-layers with phosphorus concentrations up to 4.4% were grown on GaN/Si(111) substrates by metal organic vapour phase epitaxy. The growth temperature and phosphine flows were varied in order to investigate the growth characteristics of the GaPN layers. The layers were investigated by X-ray diffraction, transmission electron diffraction, energy dispersive X-ray measurements, scanning electron microscopy, transmission electron microscopy, and photoluminescence. Singlecrystalline wurtzite-type epitaxial GaPN(0001) layers were obtained for x<0.05. For such layers X-ray and transmission electron diffraction measurements show a reduction of both the c- and a-latticeparameters without a change of the wurtzite-type crystal structure, thus indicating that phosphorus is incorporated as P 3+ or P 5+ likely substituting the Gallium lattice sites of the GaN-crystal, i.e. the formation of Ga 1-x P x N and not GaN 1-x P x as might be expected. For higher phosphorous contents phase separation effects and a variety of different phases were observed.