Dislocations in GaN single crystal were studied by means of spectral cathodoluminescence mapping and defect selective etching. It was shown that the c- type screw dislocations were not recombination active. The recombination strength of the a- and (a+c)-type dislocations was influenced by impurity gettering. While fresh dislocations exhibited a cathodoluminescence contrast of 0.01–0.05 in accordance with intrinsic dislocation states, grown in dislocations show a contrast of 0.25. From the analysis of spectral cathodoluminescence maps, it was found that impurities such as O and Si were depleted in the neighborhood of the dislocations. The increased contrast was explained by a reduced screening of the electrical field of the dislocation.

Nonradiative Recombination At Threading Dislocations in n-type GaN - Studied by Cathodoluminescence and Defect Selective Etching. M.Albrecht, J.L.Weyher, B.Lucznik, I.Grzegory, S.Porowski: Applied Physics Letters, 2008, 92[23], 231909