Browsing by Author "Huang, Y. S."

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Carrier Dynamics and Dynamic Band-Bending in Type-II ZnTe/ZnSe Quantum Dots
(2013-11-01)
Syperek, M.
;
Misiewicz, J.
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Chan, C. H.
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Dumcenco, D. O.
;
Huang, Y. S.
Carrier dynamics and dynamic band-bending in self-assembled ZnTe/ZnSe quantum dots have been studied by means of time-resolved photoluminescence experiment at low temperatures. The experiment reveals clearly type-II character of the confinement potential in the dot manifested in: (i) long photoluminescence decay time constant of 28-35 ns, and (ii) temporal shift of the quantum dot peak emission towards low energy following the laser pulse excitation. The magnitude of the spectral shift Delta E depends on the dot size and the power density of excitation pulse. For the dots under study and given experimental conditions Delta E approximate to 28 divided by 42 meV.
Electrical measurements on iridium dioxide nanorods
(2006)
Lin, Y. H.
;
Lee, T. C.
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Lin, J. J.
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Chang, H. M.
;
Huang, Y. S.
Iridium dioxide (IrO2) nanorods have been prepared by metal-organic chemical vapor deposition method. Applying the standard electron-beam lithography technique, a single nanorod with a diameter of I 10 nm is contacted by three Cr/Au fingers from above. The resistance measurements on this nanorod have been performed between 10 and 300 K, using different probe configurations. We observe that the resistivity rho of the nanorod has a value <= 120 mu Omega cm at 300 K. On the other hand, the temperature dependence of the contact resistance R obeys the law logR proportional to T-1/2 below 100 K. The conduction process through the contact is ascribed to the transport of electrons via hopping in granular metals accidentally formed at the contact region.
Electrical transport studies of individual IrO(2) nanorods and their nanorod contacts
(2008-01-30)
Lin, Y. H.
;
Sun, Y. C.
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Jian, W. B.
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Chang, H. M.
;
Huang, Y. S.
We have studied the electrical transport properties of individual single-crystalline IrO(2) nanorods prepared by the metal-organic chemical vapour deposition method. With the help of the standard electron-beam lithographic technique, individual nanorods are contacted by Cr/Au submicron electrodes from above. Utilizing two-probe, three-probe and four-probe measurement configurations, not only the intrinsic electrical transport properties of the individual nanorods but also the electronic contact resistances, Rc(T), have been determined from 300 K down to liquid-helium temperatures. Our measured resistivity behaviour of the nanorods is in close agreement with the current theoretical understanding of this rutile material. On the other hand, we found that the temperature behaviour of the electronic contact resistance obeys the law log R(C) alpha T(-1/2) over an extremely wide temperature range, from approximately 100 K down to liquid-helium temperatures. This latter conduction process is ascribed to the hopping of electrons through nanoscale Cr granules and/or an amorphous coating incidentally formed at the interface between the submicron Cr/Au electrode and the nanorod.
Electrical transport studies of individual IrO2 nanorods and their nanorod contacts
(2008-01-30)
Lin, Y. H.
;
Sun, Y. C.
;
Jian, W. B.
;
Chang, H. M.
;
Huang, Y. S.
We have studied the electrical transport properties of individual single-crystalline IrO2 nanorods prepared by the metal-organic chemical vapour deposition method. With the help of the standard electron-beam lithographic technique, individual nanorods are contacted by Cr/Au submicron electrodes from above. Utilizing two-probe, three-probe and four-probe measurement configurations, not only the intrinsic electrical transport properties of the individual nanorods but also the electronic contact resistances, Rc(T), have been determined from 300 K down to liquid-helium temperatures. Our measured resistivity behaviour of the nanorods is in close agreement with the current theoretical understanding of this rutile material. On the other hand, we found that the temperature behaviour of the electronic contact resistance obeys the law log R-C alpha T-1/2 over an extremely wide temperature range, from approximately 100 K down to liquid-helium temperatures. This latter conduction process is ascribed to the hopping of electrons through nanoscale Cr granules and/or an amorphous coating incidentally formed at the interface between the submicron Cr/Au electrode and the nanorod.
Photoluminescence of localized excitons in ZnCdO thin films grown by molecular beam epitaxy
(2016-07)
Wu, T. Y.
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Huang, Y. S.
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Hu, S. Y.
;
Lee, Y. C.
;
Tiong, K. K.
We have investigated the luminescence characteristics of Zn1-xCdxO thin films with different Cd contents grown by molecular beam epitaxy system. The temperature-dependent photoluminescence (PL) and excitation power-dependent PL spectra were measured to clarify the luminescence mechanisms of the Zn1-xCdxO thin films. The peak energy of the Zn1-xCdxO thin films with increasing the Cd concentration is observed as redshift and can be fitted by the quadratic function of alloy content. The broadened full-width at half-maximum (FWHM) estimated from the 15 K PL spectra as a function of Cd content shows a larger deviation between the experimental values and theoretical curve, which indicates that experimental FWHM values are affected not only by alloy compositional disorder but also by localized excitons occupying states in the tail of the density of states. The Urbach energy determined from an analysis of the lineshape of the low-energy side of the PL spectrum and the degree of localization effect estimated from the temperature-induced S-shaped PL peak position described an increasing mean exciton-localization effects in ZnCdO films with increasing the Cd content. In addition, the PL intensity and peak position as a function of excitation power are carried out to clarify the types of radiative recombination and the effects of localized exciton in the ZnCdO films with different Cd contents. (C) 2016 Elsevier Ltd. All rights reserved.
Photoluminescence properties of MgxZn1-xO films grown by molecular beam epitaxy
(2017-02-01)
Wu, T. Y.
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Huang, Y. S.
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Hu, S. Y.
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Lee, Y. C.
;
Tiong, K. K.
The optical properties of MgxZn1-xO films with x=0.03, 0.06, 0.08, and 0.11 grown by molecular beam epitaxy (MBE) have been studied by temperature-dependent photoluminescence (PL) measurement. It is presented that the full-width at half-maximum (FWHM) of the 12 K PL spectrum of MgZnO films increases with increasing Mg concentration and would deviate significantly from the simulation curve of Schubert model with higher Mg contents. The abnormal broader PL FWHM is inferred from larger compositional fluctuation by incorporating higher Mg contents, which results in larger effect of excitonic localization to induce more significant S-shaped behavior of the PL peak energy with temperature dependence. Additionally, the degree of localization increases as the linear proportion of the PL FWHM, indicating that the excitonic behavior in MgZnO films belong to the strong localization effect.
The effect of a concentration gradient on interfacial reactions in microburaps of Ni/SnAg/Cu during liquid-state soldering
(2012-05-01)
Huang, Y. S.
;
Hsiao, H. Y.
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Chen, Chih
;
Tu, K. N.
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材料科學與工程學系
We report new findings in Ni/SnAg solder/Cu microbumps having a reduced solder thickness in the range of 40-10 mu m; the growth rate of the intermetallic compounds depends strongly on the solder thickness. In the Ni/40 mu m solder/Cu samples., the compound which grew on the Ni side grew slightly faster than that on the Cu side. However, the growth reverses as the solder thickness decreases below 20 pm due to the change in Cu and Ni concentration gradients in the solder. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Wire-like characteristics in stacked InAs/GaAs quantum dot superlattices for optoelectronic devices
(2007-09-01)
Chen, T. T.
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Chen, Y. F.
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Wang, J. S.
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Huang, Y. S.
;
Hsiao, R. S.
The wire-like characteristics of stacked InAs/GaAs quantum dot (QDs) superlattices induced by the vertically electronic coupling effect were demonstrated by surface photovoltaic and photoluminescence measurements. It was found that the surface photovoltaic signal can be enhanced by up to more than 100 times due to the wire-like behavior along the growth direction. We also found that the emission from the cleaved edge surface is strongly anisotropic, which suggests a possibility of fine tuning the polarization by changing the spacer thickness. Additionally, the electroluminescence of stacked QDs near 1.3 mu m based on the wire-like characteristics has a much better performance than that of uncoupled QDs.