Characterization of InGaN thin films using high-resolution x-ray diffraction

Wurtzite InGaN thin films grown by metalorganic chemical vapor deposition o n sapphire substrates with and without GaN buffer layers are investigated b y high-resolution x-ray diffraction measurements. The structural quality, l attice constants, strain, and indium composition of 100 nm thick films with In concentrations up to 33% are evaluated by measuring symmetric (00.2) an d asymmetric (20.5) reflexes. The quality of the InGaN layers with widely d ifferent biaxial stress is measured and compared. An analytical solution fo r the determination of the In content of strained epitaxial layers is intro duced. The results show that neglecting the strain can result in a severe m iscalculation of the In concentration. (C) 2000 American Institute of Physi cs. [S0003-6951(00)02804-7].