The dislocation density in free-standing GaN wafers was measured by using atomic force microscope imaging of chemical mechanically polished samples and with transmission electron microscopy. Etch pits were introduced after chemical mechanical polishing of the Ga side of the GaN wafer and the pits easily imaged with the atomic force microscope. Transmission electron microscopy was also utilized to measure the dislocation density. Good agreement was found between the dislocation density measured by transmission electron microscopy and the etch pit density measured by atomic force microscope, demonstrating that chemical mechanical polish of the GaN(00▪1) surface decorates threading dislocations and that the atomic force microscope technique provided a reasonably accurate and convenient measure of the dislocation density.

Chemical Mechanical Polishing for Decoration and Measurement of Dislocations on Free-Standing GaN Wafers. X.Xu, R.P.Vaudo, G.R.Brandes, J.Bai, P.I.Gouma, M.Dudley: Physica Status Solidi C, 2003, 0[7], 2460-3