The Role of the Nucleation Annealing Temperature Annealing on the Exfoliation of Hydrogen-Implanted GaN

Abstract

GaN exfoliation of ~ µm thick layers was achieved - thicker than has been reported elsewhere - due to an understanding of the introduction and evolution of strain-related defects produced during hydrogen implantation. Analysis and modeling of the strain via triple axis diffraction and SRIM calculations showed one strained region near the surface and the second at the projected range. After annealing at temperatures up to 450 °C (1-40 hours), the surface strain decreases, whereas the strain near the projected range decreased monotonically as the annealing temperatures increased to 300 °C but showed a reversal at higher temperatures. This led to a two step exfoliation process with a low temperature step performed for 20 hours followed by high temperature annealing (850 °C). For a 150 °C first step, the combination produced a series of small (< 1 µm) blisters whereas a 375 °C first step combination produced 5-10 µm-sized exfoliated sections.