Published online by Cambridge University Press: 01 February 2011
Uncracked HVPE-GaN layers of different thicknesses were investigated using high resolution x-ray diffraction at variable temperatures. The absolute lattice parameters as well as the wafer curvature were measured simultaneously at different temperatures. All samples were found to be under biaxial tension at growth temperature. At room temperature the GaN film is under biaxial compression while the substrate is tensile strained. A simulation of the stress and curvature of the heterostructures was performed for different thicknesses of the films and substrates and a good agreement was found with the experimentally determined values.