The influence of free-carrier concentration on the PEC etching of GaN: A calibration with Raman spectroscopy

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 micro-Raman 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.