Microstructural evolution of radiation induced defects in ZnO during isochronal annealing

In this study we discuss the microstructural changes after electron and proton irradiation and the thermal evolution of the radiation induced defects during isochronal annealing. The nominally undoped samples were irradiated either with 3 MeV protons to a fluence of 1.2×10¹⁸ p/cm² or with 1 MeV electrons to a fluence of 1×10¹⁸ e/cm². The investigation was performed with positron lifetime and Doppler-broadening measurements. The measurements were done at room temperature and in some cases down to 10 K to investigate the thermal dependence of the trapping characteristics of the positrons.