Defects induced by MeV H~+ implantation for exfoliating of freestanding GaN film

摘要

High-energy ion slicing is promising to produce the free-standing GaN films with thickness in the range of 10-20 mu m, which would promote the mass applications of GaN substrates. In this paper, bulk GaN was implanted by 1.6 MeV H ions with the mean projected range R-p of around 17 mu m and the thermal evolution of the H-induced defects was investigated in detail. Due to the migration-coalescence mechanism, the H-induced point defects gather to form the initial cavity defects which grow up via the Ostwald ripening mechanism. The cavity defect distribution is determined by the distributions of the implanted hydrogen and the implantation-induced damages. The area ratio of cavity defects in the center damage band of the 1.6 MeV sample was around 3.4%. Annealing at higher temperature enhances the defect migration and recovery. Larger H ion fluence or higher annealing temperature is required to accomplish the exfoliation of a free-standing GaN thick film.