Microstructural characterisation of GaN(As) films grown on (001)GaP by molecular beam epitaxy

Samples of GaN(As)/(001)GaP grown by molecular beam epitaxy and studied using transmission electron microscopy, have been found to exhibit increasing amounts of zincblende GaN within the deposited films with increasing As flux and independent of the N flux used. All of the samples grown at 620 degrees C contained phases of GaAs, wurtzite GaN and zincblende GaN, while there was no evidence for the formation of the ternary alloy Ga(As,N), Zincblende GaN was found to form immediately in the presence of an As flux, while wurtzite GaN formed in the absence of As. A sample grown at 700 degrees C under the highest As flux exhibited single crystal zincblende GaN. Differential cross-diffusion of both N and As with P was observed, and was associated with the formation of V-shaped pits in the substrate.