Large areas of electrically active regions of in-homogeneities have been revealed by the electroless photo-etching (PEC) method in GaN layers grown by the hydride vapor phase epitaxy (HVPE) technique. Variations in the local etch rate have been correlated with the variations in the free-carrier concentrations as determined by microRaman spectroscopy. The etch rate decreased linearly with the log of the carrier concentration. The latter could change by more than two orders of magnitude on the same sample. (c) 2007 Elsevier B.V. All rights reserved.