Investigation into the influence of buffer and nitrided layers on the initial stages of GaN growth on InSb (100)

Abstract

Radio frequency plasma-assisted molecular beam epitaxy (MBE) growth of GaN on InSb (100) has been investigated. This combination is interesting because a 45° rotation of a cubic epitaxial GaN layer could result in a nearly “lattice-matched” system. The growth of low-temperature buffer layers and initial substrate nitridation at 275°C on the morphology of the subsequent growth at 450°C were considered. Nitridation produced a smooth, mixed InN and Sb–N layer, whilst annealing to 450°C resulted in the loss of the Sb nitride component and disruption of the InN, causing exposure of the underlying substrate and surface roughening. Similarly thin buffer layers (∼8 Å) were found to crystallise and island at 450°C but allowed substrate damage. By contrast, thicker buffer layers (∼80 Å) remained smooth and continuous and protected the substrate but did not crystallise. Subsequent growth morphologies reflected the surface quality of the underlying layers, however all layers were polycrystalline wurtzite GaN and no evidence was found for crystalline cubic GaN formation.