Article Title

Temperature-dependent photoconductance of heavily doped ZnO nanowires

Authors

Dongdong Li, Departments of Physics and Electrophysics, University of Southern California, Los Angeles, CA 90089, USA
Liang Zhao, Departments of Physics and Electrophysics, University of Southern California, Los Angeles, CA 90089, USA
Ruqian Wu, Department of Physics, University of California, Irvine, CA 92697, USA
Carsten Ronning, Institute of Solid State Physics, University of Jena, D-07743, Germany
Jia G. Lu, Departments of Physics and Electrophysics, University of Southern California, Los Angeles, CA 90089, USA

Keywords

ZnO, nanowire, doping, semiconductor-to-metal transition, photoconductance, impurity states

Abstract

Ga-doped ZnO nanowires have been synthesized by a pulsed laser chemical vapor deposition method. The crystal structure and photoluminescence spectra indicate that the dopant atoms are well integrated into the ZnO wurtzite lattice. The photocurrent properties at different temperatures have been systematically investigated for nanowires configured as a three-terminal device. Among the experimental highlights, a pronounced semiconductor-to-metal transition occurs upon UV band-to-band excitation. This is a consequence of the reduction in electron mobility arising from the drastically enhanced Coulomb interactions and surface scattering. Another feature is the reproducible presence of two resistance valleys at 220 and 320 K upon light irradiation. This phenomenon originates from the trapping and detrapping processes in the impurity band arising from the native defects as well as the extrinsic Ga dopants. This work demonstrates that due to the dimensional confinement in quasi-one-dimensional structures, enhanced Coulomb interaction, surface scattering, and impurity states can significantly influence charge transport.

Graphical Abstract

DOI

https://doi.org/10.1007/s12274-011-0158-1

Publisher

Tsinghua University Press

Recommended Citation

Dongdong Li,Liang Zhao,Ruqian Wu,Carsten Ronning,Jia G. Lu, Temperature-dependent photoconductance of heavily doped ZnO nanowires. NanoRes.2011, 4(11): 1110-1116