Quantum-interference transport through surface layers of indium-doped ZnO nanowires
Shao-Pin Chiu1*, Juhn-Jong Lin1,2
1Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan
2Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
* presenting author:邱劭斌, email:fluentbb@gmail.com
We have fabricated indium-doped ZnO (IZO) nanowires (NWs) and carried out four-probe electrical-transport measurements on two individual NWs with geometric diameters of ≈70 and ≈90 nm in a wide temperature T interval of 1–70 K. The NWs reveal overall charge conduction behavior characteristic of disordered metals. The T-dependence resistance R(T) and magneto-resistance (MR) in different T intervals are consistent with the theoretical predictions of the one- (1D), two- (2D) or three-dimensional (3D) weak-localization (WL) and the electron–electron interaction (EEI) effects. In particular, a few dimensionality crossovers in these two effects are observed. These crossover phenomena are consistent with the model of a ‘core–shell-like structure’ in individual IZO NWs, where an outer shell of thickness t ('15–17 nm) is responsible for the quantum-interference transport. In the WL effect, as the electron dephasing length Lϕ gradually decreases with increasing T from 1 K, a 1D-to-2D dimensionality crossover takes place around a characteristic temperature where Lϕ approximately equals an effective NW diameter d , which is slightly smaller than the geometric diameter. As T further increases, a 2D-to-3D dimensionality crossover occurs around another characteristic temperature where Lϕ approximately equals t ( < d). In the EEI effect, a 2D-to-3D dimensionality crossover takes place when the thermal diffusion length LT progressively decreases with increasing T and approaches t. This work strongly indicates that the surface-related conduction processes are essential to doped semiconductor nanostructures.

Keywords: Indium-doped ZnO (IZO) nanowires, Surface-related conduction, Weak-localization effect, Electron-electron Interaction