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 MOVPE. EBSD was used to confirm the orientation of the prisms, and deformation was observed to occur via 2nd order pyramidal slip on the {11 2 2} 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 0.17 ± 0.05 × b3 (b is the Burgers vector), and the activation energy was 0.9 ± 0.2 eV, consistent with lattice-controlled dislocation glide.