Characterization and modeling of a ZnO nanowire ultraviolet photodetector with graphene transparent contact
- Institut d'Electronique Fondamentale, UMR 8622 CNRS, University Paris Sud XI, 91405 Orsay cedex (France)
- St. Petersburg Academic University, Nanotechnology Research and Education Centre, Russian Academy of Science, Khlopina 8/3, 194021 St. Petersburg (Russian Federation)
- Laboratoire d'Electrochimie, Chimie des Interfaces et Modélisation pour l'Energie, UMR-CNRS 7575, Ecole Nationale Supérieure de Chimie de Paris, 11 rue P. et M. Curie, 75231 Paris cedex 05 (France)
We report the demonstration of a ZnO nanowire ultraviolet photodetector with a top transparent electrode made of a few-layered graphene sheet. The nanowires have been synthesized using a low-cost electrodeposition method. The detector is shown to be visible-blind and to present a responsivity larger than 10{sup 4} A/W in the near ultraviolet range thanks to a high photoconductive gain in ZnO nanowires. The device exhibits a peak responsivity at 370 nm wavelength and shows a sub bandgap response down to 415 nm explained by an Urbach tail with a characteristic energy of 83 meV. The temporal response of the detector and the power dependence are discussed. A model of the photoconductive mechanism is proposed showing that the main process responsible for the photoconductive gain is the modulation of the conducting surface due to the variation of the surface depletion layer and not the reduction of recombination efficiency stemming from the electron-hole spatial separation. The gain is predicted to decrease at high incident power due to the flattening of the lateral band bending in agreement with experimental data.
- OSTI ID:
- 22266100
- Journal Information:
- Journal of Applied Physics, Vol. 114, Issue 23; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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