A comparative study of the structural properties of InGaN/GaN quantum wells determined by X-ray diffraction, high-angle annular dark-field imaging and energy-filtered TEM

摘要

Using energy filtered transmission electron microscopy (EFTEM) and high-angle annular dark-field (HAADF) imaging, we have attempted to verify the composition and thickness of a set of InGaN/GaN multiple quantum wells as deduced from low and high-resolution x-ray diffraction (XRD) rocking curves of the out of plane (0002) reflection. We show that where variations in well and barrier thickness occur the XRD/TEM agreement is poor, but that statistical variations in the indium concentration are relatively benign. General agreement exists between HAADF and XRD for well and barrier thickness, but not between EFTEM and XRD for composition measurements.