Browsing by Author "Wu, Chih-Yuan"

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Comment on 'Electron-phonon scattering in Sn-doped In(2)O(3) FET nanowires probed by temperature-dependent measurements'
(2009-11-18)
Lin, Juhn-Jong
;
Wu, Chih-Yuan
;
電子物理學系
;
物理研究所
;
Department of Electrophysics
We point out that the recently reported electrical quantities and transport behavior in a Sn-doped indium oxide FET nanowire (Berengue et al 2009 Nanotechnology 20 245706) should require serious reevaluation.
Comment on 'Electron-phonon scattering in Sn-doped In2O3 FET nanowires probed by temperature-dependent measurements'
(2009-11-18)
Lin, Juhn-Jong
;
Wu, Chih-Yuan
;
電子物理學系
;
物理研究所
;
Department of Electrophysics
We point out that the recently reported electrical quantities and transport behavior in a Sn-doped indium oxide FET nanowire (Berengue et al 2009 Nanotechnology 20 245706) should require serious reevaluation.
Electrical conduction processes in ZnO in a wide temperature range 20-500 K
(2011-09-15)
Lien, Chien-Chi
;
Wu, Chih-Yuan
;
Li, Zhi-Qing
;
Lin, Juhn-Jong
;
電子物理學系
We have investigated the electrical conduction processes in as-grown and thermally cycled ZnO single crystal as well as as-grown ZnO polycrystalline films over the wide temperature range 20-500 K. In the case of ZnO single crystal between 110 and 500 K, two types of thermal activation conduction processes are observed. This is explained in terms of the existence of both shallow donors and intermediately deep donors that are consecutively excited to the conduction band as the temperature increases. By measuring the resistivity rho(T) of a given single crystal after repeated thermal cycling in vacuum, we demonstrate that oxygen vacancies play an important role in governing the shallow donor concentrations but leave the activation energy (similar or equal to 27 +/- 2 meV) largely intact. In the case of polycrystalline films, two types of thermal activation conduction processes are also observed between similar to 150 and 500 K. Below similar to 150 K, we found an additional conductionprocess due to the nearest-neighbor-hopping conduction mechanism, which takes place in the shallow impurity band. As the temperature further decreases below similar to 80 K, a crossover to the Mott variable-range-hopping conduction process is observed. Taken together with our previous measurements on rho(T) of ZnO polycrystalline films in the temperature range 2-100 K [Y. L. Huang et al., J. Appl. Phys. 107, 063715 (2010)], this work establishes a quite complete picture of the overall electrical conduction mechanisms in the ZnO material from liquid-helium temperatures up to 500 K. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3638120]
Electron dephasing in homogeneous and inhomogeneous indium tin oxide thin films
(2012-03-05)
Wu, Chih-Yuan
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Lin, Bo-Tsung
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Zhang, Yu-Jie
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Li, Zhi-Qing
;
Lin, Juhn-Jong
The electron dephasing processes in two-dimensional homogeneous and inhomogeneous indium tin oxide thin films have been investigated in a wide temperature range 0.3-90 K. We found that the small-energy-transfer electron-electron (e-e) scattering process dominated the dephasing from a few kelvins to several tens of kelvins. At higher temperatures, a crossover to the large-energy-transfer e-e scattering process was observed. Below about 1 to 2 K, the dephasing time tau(phi) revealed a very weak temperature dependence, which intriguingly scaled approximately with the inverse of the electron diffusion constant D, i.e., tau(phi)(T approximate to 0.3 K) proportional to 1/D. Theoretical implications of our results are discussed. The reason why the electron-phonon relaxation rate is negligibly weak in this low-carrier-concentration material is presented.
Free-electronlike diffusive thermopower of indium tin oxide thin films
(2010-12-15)
Wu, Chih-Yuan
;
Tra Vu Thanh
;
Chen, Yi-Fu
;
Lee, Jui-Kan
;
Lin, Juhn-Jong
We report our measurements of thermopower, S (T), on a series of indium tin oxide thin films from 300 down to 5 K to extract the carrier concentration n. The temperature behavior of S (T) below 300 K can be essentially described by a prevailing linear diffusive contribution. In this wide temperature interval, the phonon-drag thermopower is negligible relative to the diffusive thermopower. Therefore, the free-electronlike characteristic is clearly addressed. It should be stressed that linearity in S(d) from liquid-helium temperatures all the way up to room temperatures is seldom seen even in simple metals. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3524522]
Ge/Al bilayer thin film for optical write-once media
(2007-01-01)
Wu, T. H.
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Kuo, P. C.
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Chen, Jung-Po
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Wu, Chih-Yuan
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Yen, Po-Fu
Ge/Al bilayer thin films are prepared by magnetron sputtering. Thermal analysis shows that the phase change of the film occurs at 275 degrees C. Contrasts at 650 rim and 405 nm wavelength are 71.4% and 31.1% respectively.
Microstructure and recording mechanism of Ge/Au bilayer media for write-once optical disc
(2007-04-09)
Wu, T. H.
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Kuo, P. C.
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Fang, Yen-Hsiang
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Chen, Jung-Po
;
Yen, Po-Fu
The recording mechanism of Ge/Au bilayer and its dynamic tests for write-once blue laser high density DVD (HD DVD) are investigated. It is found that Ge2Au3 phase is nucleated between amorphous Ge and crystalline Au layer after room temperature deposition. Crystallization of Ge/Au interface layer at 170-190 degrees C is induced by the nucleated Ge2Au3 sites at the interface, the bilayer structure is further heated to 200-450 degrees C. After heating above 320 degrees C, crystallized Ge are segregated at the grain boundary. The dynamic test results show that this Ge/Au bilayer films can be applied to 1x-2x HD DVD-R. (c) 2007 American Institute of Physics.
Temperature dependence of resistance and thermopower of thin indium tin oxide films
(2010-09-30)
Lin, Bo-Tsung
;
Chen, Yi-Fu
;
Lin, Juhn-Jong
;
Wu, Chih-Yuan
;
電子物理學系
We have measured the resistance and thermopower of a series of RF sputtered and annealed indium tin oxide (ITO) thin films from 300 K down to liquid-helium temperatures. Thermal annealing was performed to modulate the levels of disorder (i.e., resistivity) of the samples. The measured resistances are well described by the Bloch-Grilneisen law between 150 and 300 K, suggesting that our thin films are metallic. At lower temperatures, a resistance rise with decreasing temperature was observed, which can be quantitatively ascribed to the two-dimensional electron-electron interaction and weak-localization effects. The thermopowers in all samples are negative and reveal fairly linear temperature dependence over the whole measurement temperature range, strongly indicating free-electron like conduction characteristics in ITO thin films. As a result, the carrier concentration in each film can be reliably determined. This work demonstrates that ITO films as thin as 15 nm thick can already possess high metallic conductivity. (C) 2010 Elsevier B.V. All rights reserved.
Temperature dependence of resistance and thermopower of thin indium tin oxide films
(2010-09-30)
Lin, Bo-Tsung
;
Chen, Yi-Fu
;
Lin, Juhn-Jong
;
Wu, Chih-Yuan
;
電子物理學系
We have measured the resistance and thermopower of a series of RF sputtered and annealed indium tin oxide (ITO) thin films from 300 K down to liquid-helium temperatures. Thermal annealing was performed to modulate the levels of disorder (i.e., resistivity) of the samples. The measured resistances are well described by the Bloch-Grilneisen law between 150 and 300 K, suggesting that our thin films are metallic. At lower temperatures, a resistance rise with decreasing temperature was observed, which can be quantitatively ascribed to the two-dimensional electron-electron interaction and weak-localization effects. The thermopowers in all samples are negative and reveal fairly linear temperature dependence over the whole measurement temperature range, strongly indicating free-electron like conduction characteristics in ITO thin films. As a result, the carrier concentration in each film can be reliably determined. This work demonstrates that ITO films as thin as 15 nm thick can already possess high metallic conductivity. (C) 2010 Elsevier B.V. All rights reserved.