Electron capture behaviours for major traps in thin epitaxial and thick free-standing GaN samples were experimentally and theoretically studied by using deep-level transient spectroscopy. According to the logarithmic dependence of the deep level transient spectroscopy signal upon the filling pulse width, most of the traps in thin epitaxial GaN layers with high dislocation density behaved as line defects. In sharp contrast, the same traps in thick free-standing GaN layers with low dislocation density behaved as point defects. The most likely explanation for these phenomena was that the electron traps in question tend to segregate around dislocations, when present in large numbers.

Dislocation-Related Electron Capture Behavior of Traps in n-Type GaN. Z.Q.Fang, D.C.Look, L.Polenta: Journal of Physics - Condensed Matter, 2002, 14[48], 13061-8