SPACE-CHARGE LAYER, INTRINSIC 'BULK' AND SURFACE COMPLEX DEFECTS IN ZnO NANOPARTICLES - A HIGH-FIELD ELECTRON PARAMAGNETIC RESONANCE ANALYSIS

摘要

The defect structure of ZnO nanoparticles is characterized by means of high-field electron paramagnetic resonance (EPR) spec-troscopy. Different point and complex defects could be identified, located at the "bulk" or the surface region of the nanoparticles. In particular, by exploiting the enhanced g-value resolution at a Larmor frequency of 406.4 GHz, it could be shown that the resonance commonly observed at g = 1.96 is comprised of several overlapping resonances from different defects. Based on the high-field EPR analysis, the development of a space-charge layer could be monitored that consists of (shallow) donor-type V_O~· defects at the "bulk" and acceptor-type V'_(Zn) and complex (Zn_i~· - V'_(zn))~× defects at the surface. Application of a core-shell model allows to determine the thickness of the depletion layer to 1.0nm for the here studied compounds [J.J. Schneider et al, Chem. Mater. 22, 2203 (2010)].