Defects in ZnO Nanoparticles

Zinc oxide (ZnO) has a paramount potential for opto-electronic applications. In this work, we study defect properties of ZnO nanoparticles, grown by a solid-state pyrolytic reaction method, using IR spectroscopy. A series of IR spectral lines have been observed at liquid-helium temperatures with an acceptor hole binding energy of $\sim $ 0.4eV. Deuterium-grown samples reveal no isotopic shift for the lines, indicating they are electronic and not vibrational. Furthermore, electron paramagnetic resonance (EPR) showed lines at g = 1.96 and g = 2.003. The former is assigned as shallow donors, whereas the latter may be attributed to holes on oxygen atoms which surround zinc vacancies.