Clusterization of vacancy defects in ZnO irradiated with 2 MeV O+

Slow positrons have been used to study ZnO layers grown on a-axis sapphire and irradiated by 2 MeV O+ ions to fluences from 1012 cm−2 to 1017 cm−2. At low fluences Zn vacancies are observed, and their introduction rate is estimated as 2000 cm−1. At the highest fluences of 1016–1017 cm−2 vacancy clusters are formed. The extent of the primary damage and its recovery is discussed.