Extraction of plasticity parameters of GaN with high temperature, in situ micro-compression

Micro-pillar compression has been utilised in a novel elevated temperature technique, in situ in the SEM to characterise the plasticity of gallium nitride (GaN) {0001}-oriented euhedral prisms grown by metallorganic vapor phase epitaxy. Electron backscatter diffraction was used to confirm the orientation of the prisms, and deformation was observed to occur via 2nd order pyramidal slip on the {11image2}〈11image3〉 slip system. Analysis of the micro-compression data allowed extraction of fundamental deformation parameters of GaN from 24.5 to 479.3 °C. The strain rate sensitivity parameter was determined to be 0.0234 ± 0.0073 both by constant strain rate micro-compressions and micro-compression strain rate jump tests. The measured activation volume was 3.88 ± 0.13 × 10−29 m3, and the activation energy was 0.9 ± 0.2 eV.