Browsing by Author "Lin, Bo-Tsung"

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Electron dephasing in homogeneous and inhomogeneous indium tin oxide thin films
(2012-03-05)
Wu, Chih-Yuan
;
Lin, Bo-Tsung
;
Zhang, Yu-Jie
;
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.
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.