Effect of Defects on the Behavior of ZnO Nanoparticle FETs

Anthony J. Morfa,*,† Nicholas Kirkwood,† Matthias Karg,† Th. B. Singh,‡ and Paul Mulvaney†

†School of Chemistry & Bio21 Institute, University of Melbourne, Parkville, 3010, Victoria, Australia

‡CSIRO Division of Materials Science and Engineering, Clayton, 3169, Victoria, Australia

ABSTRACT: The effects of ZnO crystal defects and the ubiquitous defect fluorescence on the electronic properties of nanocrystal thin-films were determined. Films were prepared from particles prepared in DMSO with controllable defect fluorescence. Particles were determined to range in size from 5 to 12 nm on average, with little bearing on the electronic properties. Thin film electron mobilities were found to decrease from 0.04 cm2 V^1 s^1 to 0.008 cm2 V^1 s^1 with decreasing defect fluorescence, indicating crystal defects are pivotal to high- mobility ZnO nanoparticle films. The threshold voltage of ZnO nanoparticle FET devices was found to decrease from 120 to 40 V while the resistivity increased 100-fold with decreasing defect fluorescence. These results are found to be in excellent agreement with theory and greatly improve our understanding of ZnO nanoparticle conduction.