Penetration effects of high-energy protons in GaN: A micro-raman spectroscopy study

Micro-Raman spectroscopy was used to examine changes of the structural and electrical properties of GaN templates submitted to high-energy proton irradiation. The locations of larger structurally damaged regions, for each proton irradiation condition, were determined by monitoring the variations of the quasilongitudinal optical phonon frequency. We observed that protons generated defect clusters, through collisions with lattice atoms, and act as carrier traps. The experimental results showed a reduction of the carrier concentrations around the estimated penetration depths for specific proton energies, which are in good agreement with the numerical simulation results. The proton-induced damage was partially healed by a thermal annealing treatment at 900°C.