Browsing by Author "Chang, Yu-Tsui"

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Excellent piezoelectric and electrical properties of lithium-doped ZnO nanowires for nanogenerator applications
(2014-09-01)
Chang, Yu-Tsui
;
Chen, Jul-Yuan
;
Yang, Tzu-Ping
;
Huang, Chun-Wei
;
Chiu, Chung-Hua
The well-aligned Li-doped zinc oxide nanowires (ZnO NWs) were successfully grown on Si substrates with seed layer by the hydrothermal method. The presence of Li in ZnO NWs is confirmed through EELS spectrum analysis. The acceptor energy level of the Li dopant is estimated to be 93.6 meV from the temperature-dependent PL spectra. From the SQUID measurements, the coercivity and saturation magnetization of the Li-doped ZnO NWs at room temperature are found to be 166 Oe and 9.64 memu/g, respectively. Additionally, the Li-doped ZnO NWFET confirms that the NWs were p-type with a high carrier mobility of 14.59 cm(2/)V s and an effective hole carrier concentration of 1.13 x 10(17) CM-3. The piezoelectric response of the Li-doped ZnO NWs produces much higher piezoelectric output current, voltage, and power than pure ZnO NWs. These results indicated that p-type ZnO NWs are a promising candidate for nanogenerator devices. (C) 2014 Elsevier Ltd. All rights reserved.
Synthesis and Characterization of One-Dimensional Ag-Doped ZnO/Ga-Doped ZnO Coaxial Nanostructure Diodes
(2014-04-09)
Chiu, Hsien-Ming
;
Chang, Yu-Tsui
;
Wu, Wen-Wei
;
Wu, Jenn-Ming
;
材料科學與工程學系
In the pursuit of high injection current diode nanodevices, entire one-dimensional (1D) ZnO coaxial nanostructures with p-n homojunctions is one of the ideal structures. In this study, we synthesized entire 1D ZnO-based coaxial homojunction diodes with p-type Ag-doped ZnO (SZO) nanostructure shells covering n-type Ga-doped ZnO (GZO) nanopagoda (NPG) cores by a metal organic chemical vapor deposition (MOCVD) technique. The entire ID SZO-GZO and SZO-ZnO coaxial nanostructures exhibit better diode characteristics, such as lower threshold voltage, better rectification ratios, and better ideality factor n, than that reported for either 2D or 2D-1D p-n heterojunction and/or homojunction diodes. The binding energies of Ga and Ag were evaluated by low-temperature and temperature-dependent photoluminescence. In comparison, the SZO-GZO coaxial p-n nanostructures display better diode performance than the SZO-ZnO ones.