Dislocation and Elastic Strain in an InN Film Characterized by Synchrotron Radiation X-Ray Diffraction and Rutherford Backscattering/Channeling

Dislocation information and strain-related tetragonal distortion as well as crystalline qualities of a 2-µm −thick InN film grown by molecular beam epitaxy (MBE) are characterized by Rutherford backscattering/channeling (RBS/C) and synchrotron radiation x-ray diffraction (SR-XRD). The minimum yield χ_min=2.5% deduced from the RBS/C results indicates a fairly good crystalline quality. From the SR−XRD results, we obtain the values of the screw and edge densities to be ρ_screw=7.0027×10⁹ and ρ_edge=8.6115×10⁹ cm⁻², respectively. The tetragonal distortion of the sample is found to be −0.27% by angular scans, which is close to the −0.28% derived by SR-XRD. The value of |e^⊥/e^|| |=0.6742 implies that the InN layer is much stiffer along the a axis than that along the c axis, where e^|| is the parallel elastic strain, and e^⊥ is the perpendicular elastic strain. Photoluminescence results reveal a main peak of 0.653 eV with the linewidth of 60 meV, additional shoulder band could be due to impurities and related defects.