Fast-Response Single-Nanowire Photodetector Based on ZnO/WS2 Core/Shell Heterostructures
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Date
2018
Authors
Butanovs, Edgars
Vlassov, Sergei
Kuzmin, Alexei
Piskunov, Sergei
Butikova, Jelena
Polyakov, Boris
Journal Title
Journal ISSN
Volume Title
Publisher
American Chemical Society
Abstract
The surface plays an exceptionally important role in nanoscale materials, exerting a strong influence on their properties. Consequently, even a very thin coating can greatly improve the optoelectronic properties of nanostructures by modifying the light absorption and spatial distribution of charge carriers. To use these advantages, 1D/1D heterostructures of ZnO/WS2 core/shell nanowires with a-few-layers-thick WS2 shell were fabricated. These heterostructures were thoroughly characterized by scanning and transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. Then, a single-nanowire photoresistive device was assembled by mechanically positioning ZnO/WS2 core/shell nanowires onto gold electrodes inside a scanning electron microscope. The results show that a few layers of WS2 significantly enhance the photosensitivity in the short wavelength range and drastically (almost 2 orders of magnitude) improve the photoresponse time of pure ZnO nanowires. The fast response time of ZnO/WS2 core/shell nanowire was explained by electrons and holes sinking from ZnO nanowire into WS2 shell, which serves as a charge carrier channel in the ZnO/WS2 heterostructure. First-principles calculations suggest that the interface layer i-WS2, bridging ZnO nanowire surface and WS2 shell, might play a role of energy barrier, preventing the backward diffusion of charge carriers into ZnO nanowire.
Description
This work was supported by the Latvian National Research Program IMIS2 and ISSP project for Students and Young Researchers Nr. SJZ/2016/6. S.P. is grateful to the ERA.Net RUS Plus WATERSPLIT project no. 237 for the financial support. S.V. is grateful for partial support by the Estonian Science Foundation grant PUT1689.
Keywords
Research Subject Categories::NATURAL SCIENCES:Physics , 1D/1D heterostructures , core/shell nanowires , photodetectors , transitional metal chalcogenides , van der Waals epitaxy