GaN epilayer grown on Sapphire by MOCVD technique was irradiated with 75MeV Sn5+ ions to a fluence of 1011, 1012, 1013 and 1014/cm2 and studied using depth-resolved positron annihilation spectroscopy. High-energy ion-induced defects were found to be Ga monovacancies, which were identified from the defect sensitive S-parameter values as well as from R-parameter values, for all fluence beyond 1011/cm2. It was also found that the concentration of vacancy defects increased with ion fluence.

Production of Vacancy Defects in High-Energy Sn-Ion Irradiated GaN - Positron Beam Doppler Broadening Study. P.Premchander, S.Abhaya, K.Sivaji, G.Amarendra, K.Baskar, Y.T.Lee: Physica B, 2006, 376-377, 507-11