Browsing by Author "Jian, Dunliang"

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Electron hopping transport in 2D zinc oxide nanoflakes
(2017-06-01)
Jian, Dunliang
;
Lai, Jian-Jhong
;
Lin, Yen-Fu
;
Zhai, Jianpang
;
Li, Irene Ling
A sequential hydrothermal process was used to synthesize ZnO nanostructures on Si substrates. The synthesized ZnO nanostructures were inspected and presented a morphology of 2D structures, named nanoflakes. These ZnO nanoflakes had a thickness of tens of nanometers. An energy dispersive x-ray spectrum revealed their composition of only Zn and O elements. In addition, its crystalline structure was investigated by high-resolution transmission electron microscopy. The nanoflakes were then dispersed for another morphology measurement using atomic force microscopy and their average thickness was determined. The dispersed nanoflakes were further contacted with metal electrodes for electron transport measurements. Through the analysis of temperature-dependent resistivity, it was confirmed that the electron transport in such ZnO nanoflakes agrees well with the theory of Mott's 2D variable range hopping. The nature of the 2D electron system in the ZnO nanoflakes points to potential applications of this 2D semiconductor as a new channel material for electronics.
Electron transport in the two-dimensional channel material - zinc oxide nanoflake
(2018-03-01)
Lai, Jian-Jhong
;
Jian, Dunliang
;
Lin, Yen-Fu
;
Ku, Ming-Ming
;
Jian, Wen-Bin
ZnO nanoflakes of 3-5 mu m in lateral size and 15-20 nm in thickness are synthesized. The nanoflakes are used to make back-gated transistor devices. Electron transport in the ZnO nanoflake channel between source and drain electrodes are investigated. In the beginning, we argue and determine that electrons are in a two-dimensional system. We then apply Mott's two-dimensional variable range hopping model to analyze temperature and electric field dependences of resistivity. The disorder parameter, localization length, hopping distance, and hopping energy of the electron system in ZnO nanoflakes are obtained and, additionally, their temperature behaviors and dependences on room-temperature resistivity are presented. On the other hand, the basic transfer characteristics of the channel material are carried out, as well, and the carrier concentration, the mobility, and the Fermi wavelength of two-dimensional ZnO nanoflakes are estimated.