Structural characterization of InN epilayers grown on r -plane sapphire by plasma-assisted MBE



The structural properties of InN films grown on r -plane (1equation image02) sapphire by plasma-assisted molecular beam epitaxy (PAMBE) using low temperature buffer layers are studied. Nonpolar a -plane (1equation image20) and semipolar s -plane (10equation image1) films were deposited depending on buffer layer and growth conditions. Single crystalline a -plane InN was grown using a GaN buffer layer following sapphire nitridation. Transmission electron microscopy (TEM) observations showed three-dimensional growth and interactions of inclined threading dislocations emanating from the buffer layer. The defect interactions gradually reduced the threading dislocation density. Semipolar s -plane was grown when a thin InN buffer layer was employed. The epilayer was found to comprise two s -plane variants. Semipolar nucleation directly on the sapphire was observed. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)