Molten KOH-based defect etching of GaN epitaxial layers, for the quantitative determination of the dislocation density, was reported. Etching process parameters were established, at 450C, that were suitable for revealing threading edge and threading screw dislocations at the same time, and thus permitted the quantitative determination of the total dislocation density in metalorganic vapor-phase epitaxially grown GaN layers. The determined dislocation numbers, in the 108/cm2 range, were correlated with the full-width at half-maximum of rocking curves of the (30¯2) reflection and with dark spots observed by cathodoluminescence of the etched GaN surfaces.

Determination of Dislocation Density in MOVPE Grown GaN Layers Using KOH Defect Etching. P.J.Wellmann, S.A.Sakwe, F.Oehlschläger, V.Hoffmann, U.Zeimer, A.Knauer: Journal of Crystal Growth, 2008, 310[5], 955-8