Mechanism of recrystallization process in epitaxial GaN under dynamic stress field - Atomistic origin of planar defect formation

TL;DR

This study investigates the atomistic mechanisms behind recrystallization in epitaxial GaN films under stress, revealing the critical role of vacancy migration in initiating dislocation dynamics and planar defect formation.

Contribution

It uncovers the atomistic origin of recrystallization in GaN, highlighting vacancy migration as the rate-limiting step in dislocation-driven defect formation.

Findings

Dislocation nucleation and climb are observed during indentation.

Vacancy migration controls the rate of recrystallization.

Planar defect migration is a key process in recrystallization.

Abstract

The mechanism of recrystallization in epitaxial (1000) GaN film, introduced by indentation technique, is probed by lattice dynamic studies using Raman spectroscopy. The recrystallized region is identified by Micro-Raman area mapping. Pop-in bursts in loading lines indicate nucleation of dislocations and climb of dislocations. These processes set in plastic motion of lattice atoms under stress field at the center of indentation for the initiation of recrystallization process. A planar defect migration mechanism is evolved. A pivotal role of vacancy migration is pointed out, for the first time, as the rate limiting factor for the dislocation dynamics initiating the recrystallization process in GaN.