Triclinic deformation of InGaN layers grown on vicinal surface of GaN (00.1) substrates

Abstract

We report on a triclinic unit cell deformation of fully strained InGaN layers grown on vicinal GaN (00.1) substrates. The samples were examined using the high-resolution X-ray diffraction (HR XRD) using a set of asymmetrical reflections and one symmetrical reflection of 00.2. The substrate miscut induced triclinic deformation of the layer unit cells, breaking the hexagonal symmetry. The experimental results are compared with predictions of the theory of elasticity. We formulate equations for unit cell parameters of layers grown on substrates cut in any direction, based on the equations given by Romanov et al. [J. Appl. Phys. 100, 023522 (2006)]. Additionally, the paper provides a recipe of the XRD measurements necessary to establish unit cell parameters (useful for composition determination of ternary compounds) of the hexagonal mismatched layers grown on off-axis substrates.