Irradiation-induced defects (60Co, 3 x 1019/cm2) in n-type epilayers on (00•1) sapphire substrates were investigated. The irradiation decreased the electron concentration in slightly-doped epilayers, but increased it in heavily doped epilayers. At the same time, the irradiation caused a decrease in electron mobility for all of the epilayers. In heavily-doped epilayers, the concentration increase continued during annealing at temperatures of up to 250C and was associated with the activation of neutral complexes. Two electron traps, of 0.155 and 0.95eV, appeared in irradiated slightly-doped epilayers. The electrical properties were restored to their original values by annealing at 550C.

Effect of Annealing on Defects in As-Grown and γ-Irradiated n-GaN Layers N.M.Shmidt, D.V.Davydov, V.V.Emtsev, I.L.Krestnikov, A.A.Lebedev, W.V.Lundin, D.S.Poloskin, A.V.Sakharov, A.S.Usikov, A.V.Osinsky: Physica Status Solidi B, 1999, 216[1], 533-6