Positron annihilation spectroscopy was used to study 2MeV 4He+-irradiated InN grown by molecular-beam epitaxy and GaN grown by metal-organic chemical-vapor deposition. In GaN, the Ga vacancies acted as important compensating centers in the irradiated material; introduced at a rate of 3600/cm. The In vacancies were introduced at a significantly lower rate of 100/cm, making them negligible in the compensation of the irradiation-induced additional n-type conductivity in InN. On the other hand, negative non-open volume defects were introduced at a rate higher than 2000/cm. These defects were tentatively attributed to interstitial N and may ultimately limit the free-electron concentration at high irradiation fluences.

Compensating Point Defects in 4He+-Irradiated InN. F.Tuomisto, A.Pelli, K.M.Yu, W.Walukiewicz, W.J.Schaff: Physical Review B, 2007, 75[19], 193201 (4pp)