A Comparative Study of Dislocations in HVPE GaN Layers by High-Resolution X-Ray Diffraction and Selective Wet Etching

It has been shown during the present study that the E-etching at elevated temperatures can be adopted for the dislocation etching in hydride vapor-phase epitaxy (HVPE) GaN layers. It has been found that the X-ray diffraction (XRD) evaluation of the dislocation density in the thicker than 6 m epilayers using conventional Williamson-Hall plots and Dunn-Koch equation is in an excellent agreement with the results of the elevated-temperature E-etching. The dislocation distribution measured for 2-inch GaN-on-sapphire substrate suggests strongly the influence of the inelastic thermal stresses on the formation of the final dislocation pattern in the epilayer.