In situ X-ray Reflectivity Measurements on Annealed InxGa1-xN Epilayer Grown by Metalorganic Vapor Phase Epitaxy

The thermal decomposition of c-plane GaN/sapphire templates was studied in a metalorganic vapor phase epitaxy (MOVPE) system installed in a laboratory-level X-ray diffractometer by using in situ X-ray reflectivity (XRR). GaN remained thermally stable in pure N-2 up to 900 degrees C, while a significant decomposition occurred at 950 degrees C. Then, thin InxGa1-xN epilayers were grown on the annealed templates at 830 degrees C. In situ XRR measurements were conducted before and after InGaN growth. By theoretical and experimental analyses of the XRR spectra, the sample structure change upon thermal annealing was clarified. Photoluminecescence (PL) and atomic force microscopy (AFM) results demonstrated that thermal annealing affected the optical properties and microstructures of InGaN films. The PL peaks from InGaN slightly blue-shifted with thermal annealing. (C) 2013 The Japan Society of Applied Physics