Plasma-assisted MBE growth of GaN and InGaN on different substrates

We investigate structural and optical properties of GaN and InGaN on sapphi re and neodymium gallate substrates, deposited by MBE using a novel RF and conventional ECR nitrogen activators. The GaN/NdGaO3 layer demonstrates hig her luminescence efficiency compared with GaN/Al2O3. Dislocation density in GaN/NdGaO3, estimated using X-ray diffraction measurements, is much less t han that in the layers on sapphire substrate (the dominant vertical screw d islocation density is 10(4) or less). The layers demonstrate a direct corre lation between the dislocation density and incorporation of oxygen and othe r contaminations determined by secondary ion mass spectroscopy measurements , with the lowest impurity concentration located in the GaN/NdGaO3 epilayer s. All the layers grown by the novel nitrogen source exhibit negligible yel low photoluminescence band independently of the substrate type. (C) 1999 El sevier Science B.V. All rights reserved.