Electric activity of charged dislocations in GaN

O. Marquardt, M. Rayson, C. Freysoldt, L. Lymperakis, M. Albrecht[*], and J. Neugebauer

Due to the lack of lattice and thermal matched substrates, growth of wurtzite GaN films results typically in high threading dislocation (TD) densities. Since the work by Lester et al. [1] there is a large controversial debate regarding the effect dislocations have on the electronic and optical properties of group III-Nitride based devices.

In a previous project we have focused on the a-type threding dislocation in GaN (b=1/3<1120>, l=[0001]) and we investigated the atomic geometry, energetics, and electronic structure of three different core structures by means of ab-initio based multiscale calculations [2]. Here we combine k.p with first principles calculations to investigate the energetics and the electronic structure of c-type screw dislocations (b=1/3<0001>, l=[1120]) in GaN.

[1] S. D. Lester, F. A. Ponce, M. G. Craford, and D. A. Steigerwald, Appl. Phys. Lett. 66, 1249 (1995).

[2] L. Lymperakis, J. Neugebauer, M. Albrecht, T. Remmele, and H. P. Strunk, Phys. Rev. Lett. 93, 196401 (2004).

[*] M. Albrecht, Leibniz-Institut für Kristallzüchtung (IKZ), Berlin