The electronic properties of the threading dislocations in undoped GaN were studied by using electron holography. The electrostatic potential profiles showed that edge, screw, and mixed dislocations were negatively charged. The line charge density at the dislocation core, defined by n electrons per unit cell along the c direction, was determined. The line charge densities for edge, screw, and mixed dislocations were about 0.3, 1.0 and 0.6 e/c, respectively. The corresponding radii of the charged core were 15, 40 and 20nm, respectively. A model was proposed for the charge distribution around dislocations.

Determination by Electron Holography of the Electronic Charge Distribution at Threading Dislocations in Epitaxial GaN. J.Cai, F.A.Ponce: Physica Status Solidi A, 2002, 192[2], 407-11