Piezoelectric field, exciton lifetime, and cathodoluminescence intensity at threading dislocations in GaN{0001}

TL;DR

This paper investigates how strain relaxation at threading dislocations in GaN{0001} generates piezoelectric charges that influence exciton dissociation and cathodoluminescence, revealing new insights into dislocation-related luminescence.

Contribution

It demonstrates that strain relaxation at dislocations produces significant piezoelectric fields affecting exciton behavior and luminescence in GaN.

Findings

Piezoelectric volume charge arises at dislocation outcrops.

Electric fields can dissociate excitons over 100 nm away.

Impact on cathodoluminescence imaging of dislocations.

Abstract

The strain field of a dislocation emerging at a free surface is partially relaxed to ensure stress free boundary conditions. We show that this relaxation strain at the outcrop of edge threading dislocations in GaN{0001} gives rise to a piezoelectric volume charge. The electric field produced by this charge distribution is strong enough to dissociate free excitons at distances over 100 nm from the dislocation line. We evaluate the impact of this effect on cathodoluminescence images of dislocations.