Molten KOH-based defect etching of GaN epitaxial layers was described for quantitative determination of the dislocation density. Etching process parameters were established at 450C that were suitable to reveal threading edge and threading screw dislocations at the same time and, hence, allow for the quantitative determination of the total dislocation density in the metal organic vapour-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 (302¯) reflection and with dark spots observed via 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