Extra half-plane shortening of dislocations as an origin of tensile strain in Si-doped (Al)GaN

J. Weinrich1,2, A. Mogilatenko1,2, F. Brunner1, C.T. Koch2, and M. Weyers1

Published in:

J. Appl. Phys., vol. 126, no. 08, pp. 085701 (2019).

Copyright © 2019 AIP Publishing LLC. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the AIP Publishing LLC.


Si doping of (Al,Ga)N layers grown by metalorganic chemical vapor deposition induces an inclination of threading dislocations (TDs). This inclination leads to a change of the extra half-plane size of edge and mixed type dislocations. Depending on the dislocation density and the doping concentration, these effects are accompanied by the generation of tensile strain, which can also lead to crack formation. Several models have been published in the past in order to explain this process. Different models result in opposite TD inclination directions with respect to the extra half-plane position. Therefore, this work examines the correlation between the extra half-plane position and the inclination direction to clarify the origin of the tensile strain increase using scanning transmission electron microscopy. With this approach, it can be unambiguously experimentally verified that Si doping leads to a shortening of the dislocations half-plane. An analysis of in situwafer curvature measurement proves that the increase of tensile strain in GaN caused by Si doping can be explained by this process. Aside from the inclination caused by Si doping, a TD inclination in undoped GaN layers has been analyzed. Possible explanations for the inclination process are discussed.

1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
2 Institute of Physics, Humboldt University of Berlin, Newtonstr. 15, 12489 Berlin, Germany