Characterization of polishing induced defects and hydrofluoric acid passivation effect in ZnO

Abstract

We used depth-resolved cathodoluminescence spectroscopy and transient photovoltage spectroscopy (T-SPS) measurements to study the spatial distributions and densities of native point defects in bulk ZnO samples subjected to mechanical polishing and how the defects change with hydrofluoric acid (HF) etching. Mechanical polishing produces Zn vacancy-related defects that deplete free carriers at depths extending to 300-500 nm, while HF etching removes/passivates these defects as well as bulk oxygen vacancy-related defects, restoring the charge carriers below the etched surface. T-SPS defect density changes with polishing/etching correlate closely with deep level transient spectroscopy densities, demonstrating the applicability of T-SPS as a non-contact quantitative defect density measurement technique. © 2013 AIP Publishing LLC.