Elastic strain in In0.18Ga0.82N layer: A combined x-ray diffraction and Rutherford backscattering/channeling study

Abstract

An InGaN layer was grown by metalorganic chemical vapor deposition on a sapphire (0001) substrate using a thick (>2.2 μm) GaN intermediate layer. The In composition, which cannot be unambiguously determined by x-ray diffraction (XRD) or by photoluminescence, was determined by Rutherford backscattering (RBS). The perpendicular and parallel elastic strain of the In0.18Ga0.82N layer, e⊥=+0.21% and e∥=−0.53%, respectively, were derived using a combination of XRD and RBS/channeling. The small ratio |e⊥/e∥|=0.40 indicates that the In0.18Ga0.82N layer is much stiffer in the c-axis direction than in the a-axis direction.