ABSTRACT
P Ruterana, V Potin, P Vermautl, G Nouet, B Barbaray, A Botchkarev 2 and H Morko~ 2
Laboratoire d'Etudes et de Recherches sur les Materiaux , UPRESA 6004 CNRS, lnstitut des Sciences de Ia Matiere et du Rayonnement, 6 Bd Marechal Juin, 14050 Caen Cedex, France. 1 Now at the Laboratoire de Metallurgie Structurale, Ecole Nationale de Chimie de Paris, 11, rue Pierre et Marie Curie, 75231 Paris Cedex 05 2 Department of Electrical Engineering, Virginia Commonwealth University, P.O. Box 843072, Richmond, V A23284-3072, USA email: ruterana@lermat8.ismra.fr
ABSTRACT: GaN layers contain large densities (1010 cm.2) of threading dislocations, nanopipes, (0001) and {ll20} stacking faults, and {1010} inversion domains. Three configurations have been found for pure edge dislocations, mainly inside high angle grain boundaries where the 4 atom ring cores can be stabilized. Two atomic configurations, related by a 116<10l0> stair rod dislocation, have been observed for the {1120} stacking fault in (Ga-Al)N layers. Such defects form on steps in epitaxial layers on the top of (0001) 6H-SiC; on (0001) sapphire, they appear on coalescence of two adjacent islands related by the 11 stacking fault. For the { 1010} inversion domain boundaries, a configuration corresponding to the Holt model was observed, as well as another with noNN or Ga-Ga bonds. The two configurations are related by a c/2 translation. These boundaries are quite efficient in minimizing the shift along c which is introduced by substrate surface steps.
