The defect states of an electron-beam irradiated GaN epilayer were characterized by capacitance–voltage and deep-level transient spectroscopy measurements. The electron irradiation was performed using 1 and 2MeV beams to doses of 1015 and 1016/cm2, respectively. The depth penetrated, in the GaN epilayer, by 1MeV electrons appeared to be about 450 to 600nm; according to capacitance–voltage measurements. Five defect states with activation energies of 0.34, 0.49 and 0.65eV - including two broad signals - were observed by deep-level transient spectroscopic measurements, and it was suggested that they might originate from crystal damage during high-energy electron irradiation.

Study on Defect States in GaN Epilayer Induced by Irradiation of High-Energy Electrons. L.Ha, D.U.Lee, J.S.Kim, E.K.Kim, B.C.Lee, D.K.Oh, S.B.Bae, K.S.Lee: Japanese Journal of Applied Physics, 2008, 47, 6867-9