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Title: Gate-tunable photocurrent in ZnO nanowires mediated by nanowire-substrate interface states

We report the observation of gate-tunable photocurrent in ZnO nanowires under optical excitation in the visible regime. Particularly, the photocurrent can be tuned by one order of magnitude with moderate changes in the backgate voltages (from −10 V to 10 V), and by more than two orders of magnitude within an extended range of the backgate voltage (several tens of volts). Using scanning photocurrent microscopy, single-nanowire photocurrent spectroscopy, and numerical calculations, we suggest that this gate tunability originates from the nanowire/substrate (Si{sub 3}N{sub 4}) interface states, where the electron occupation of these states and the excitation of electrons are controlled by the backgate voltage. This external gate tunability of the photocarrier generation facilitated by interface states provides an additional way to control photodetecting and photovoltaic properties, and this approach can also be extended to other nanostructures, such as two-dimensional semiconductors, where the surface effects are significant.
Authors:
; ; ; ;  [1]
  1. Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164 (United States)
Publication Date:
OSTI Identifier:
22412770
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ELECTRIC POTENTIAL; ELECTRONS; EXCITATION; INTERFACES; MICROSCOPY; NANOWIRES; PHOTOVOLTAIC EFFECT; SEMICONDUCTOR MATERIALS; SILICON NITRIDES; SPECTROSCOPY; SUBSTRATES; SURFACES; TWO-DIMENSIONAL SYSTEMS; ZINC OXIDES