Structural features in GaN grown on a Ge(111) substrate

Using electron microscopy, structural characterisation has been carried out on a GaN epilayer grown directly on a Ge(111) substrate using plasma assisted molecular beam epitaxy (PAMBE) without any intermediate buffer layers. It was determined that a defect with a triangular shape, initially observed with optical microscopy, is essentially a faceted void in the Ge extending from the interface into the substrate. Both hexagonal and cubic phase GaN were observed in the epilayer which may be due to temperature variation during growth. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)