Dislocation-assisted electron and hole transport in GaN epitaxial layers.

Abstract

Dislocations significantly influence carrier transport in semiconductors. While segments orthogonal to the channel act as scattering centers impeding conduction, electrically active dislocation cores can facilitate carrier transport. However, the mechanisms governing carrier transport along dislocation cores remain unclear. Here, we provide the first experimental evidence for the separate transport mechanisms of electrons and holes mediated by threading screw dislocations and threading edge dislocations in gallium nitride. Critically, we demonstrate that devices with a higher total dislocation density exhibit less degradation due to current collapse, owing to a larger proportion of edge dislocations mitigating electron trapping caused by screw dislocations. Screw dislocations promote electron leakage via horizontal potential barriers and vertically connected shallow states, while edge dislocations enhance hole transport through extended trap levels interacting with buffer defects. These findings clarify the long-standing debate on carrier-specific dislocation transport mechanisms and offer critical insights for defect engineering, epitaxial growth optimization, and the development of dislocation-enhanced semiconductor devices.