Subsurface damage in polishing–annealing processed ZnO substrates

Abstract

Positron annihilation spectroscopy and secondary ion mass spectrometry have been applied to study the evolution of polishing-induced defects in hydrothermally grown ZnO samples depending on the annealing temperature. Annealing of the as-grown ZnO wafer at 1200–1500°C is found to lead to Li accumulation in the sub-surface layer, and significant reduction of Li content in the bulk. Polishing is shown to introduce vacancy complexes involving both VZn and VO. Post-polishing annealing of hydrothermally grown ZnO with removed Li layer at 800°C reduces the concentration of polishing-induced defects below the detection limit.