A photo-electrochemical etching process was described which revealed the dislocation microstructure of n-type films by selectively removing material between dislocations. The whiskers that were formed by such etching had diameters of between 10 and 50nm and lengths of up to 1μ. A correlation between the etched features, and threading dislocations in the unetched film, was confirmed by transmission electron microscopy. Whisker formation was suggested to indicate electrical activity at the dislocations.

Gallium Nitride Whiskers Formed by Selective Photoenhanced Wet Etching of Dislocations. C.Youtsey, L.T.Romano, I.Adesida: Applied Physics Letters, 1998, 73[6], 797-9