Nanocrystals at MBE-grown GaN/GaAs(001) interfaces

Molecular beam epitaxy (MBE) growth utilising an RF-plasma nitrogen source was used to study surface reconstruction and the effects of nitridation dam age on the surface and interface morphology of GaN on GaAs(001) at 580 degr ees C. Keeping both the N-flow and plasma excitation power constant, the gr own layers were studied with the Ga-flux as a parameter. In the initial gro wth stage, a (3 X 3) surface reconstruction was observed. Samples grown und er N-rich, Ga-rich and stoichiometric conditions were characterised by high -resolution scanning electron microscopy (SEM) and atomic force microscopy (AFM) to reveal the surface morphology. The nitridation damage was characte rised by Auger-electron spectroscopy (AES), X-ray diffraction (XRD) spectro scopy and high-resolution SEM, which revealed separated GaN and GaAs phases at interfaces deeply in the substrate region, bordered by {101} and {111} facets. The defect formation at the GaN/GaAs interface depended on the N/Ga -flux ratio. (C) 2000 Elsevier Science B.V. All rights reserved.