A technique was described which was based upon photo-electrochemical wet-etching and which permitted the efficient and accurate evaluation of dislocation densities in n-type films. The etching involved dilute aqueous KOH solutions and Hg arc-lamp illumination. This produced etched so-called whiskers by selectively etching away the material around threading dislocations. The etched whiskers, each of which corresponded to a single threading dislocation, could be effectively imaged by using plan-view scanning electron microscopy. The distributions and densities of dislocations were then easily observable over very large sample areas. Transmission electron microscopy and atomic force microscopy confirmed the accuracy of the dislocation densities which were deduced by using wet etching.

Rapid Evaluation of Dislocation Densities in n-Type GaN Films Using Photoenhanced Wet Etching C.Youtsey, L.T.Romano, R.J.Molnar, I.Adesida: Applied Physics Letters, 1999, 74[23], 3537-9