Browsing by Author "Hsieh, W. H."

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Correlated Electric Fluctuations in GaN Nanowire Devices
(2009-02-01)
Li, L. C.
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Huang, S. Y.
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Wei, J. A.
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Suen, Y. W.
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Lee, M. W.
We report an experimental study on the correlation spectrums between different sections of a multicontact GaN nanowire device. Our results indicate that there exists a negative correlation between the voltage fluctuations of adjacent sections of the nanowire separated by a metal contact in the transition region between the low-frequency 1/f noise and the high-frequency white thermal noise. We suggest that this correlation is caused by the voltage fluctuation under the contact area.
Edge magnetoplasma excitations in quantum wire arrays
(2008-03-01)
Hsieh, W. H.
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Suen, Y. W.
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Lee, B. C.
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Li, L. C.
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Lee, C. P.
We report the low-temperature microwave properties of edge magneto-plasma excitations in quantum-wire arrays, fabricated from a two-dimensional electron gas in a GaAs/AlGaAs heterostructure and embedded in the slots of a 50-Omega meandering coplanar waveguide. The plot of frequency versus Landau level filling factors with strong absorption gives a series of barn-shaped curves with tops being centered in the quantum Hall effect plateaus and following a straight line through the origin. Away from the plateau center, the absorption dip becomes weaker and disappears near the plateau-plateau transition regime, qualitatively following the magneto hydrodynamic model. At frequencies above this barn-shaped part, however, we also observed unexpected resonant dips. (c) 2007 Published by Elsevier B.V.
Low cost high-efficiency high-density-plasma Silicon-based thin film solar cells with high light-soaking stability
(2012)
Hsiao, T. H.
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Shieh, J. M.
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Yu, P. C.
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Shen, C. H.
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Kao, M. H.
We investigate the performance of a single-junction amorphous Si (a-Si) and a-Si/a-Si tandem solar cells fabricated with Inductively Coupled Plasma (ICP) deposition technique. The high-density plasma resulting from high dissociation capacity of ICP enables good-quality hydrogenated Si films to be synthesized at low temperatures. High-density ICP also promotes the diffusion of reactive radicals on substrates and forms a-Si:H films with low defect density. We demonstrate single-junction a-Si solar cells and a-Si/a-Si tandem solar cell with a conversion efficiency of 9.6% and 8.8%, respectively. Highly light-soaking stable high-density plasma-fabricated a-Si and a-Si/a-Si solar cells were demonstrated with photo-induced degradation in conversion-efficiency as low as 7% and 5%, respectively.
Mobility asymmetry in InGaAs/InAlAs heterostructures with InAs quantum wires
(2007-02-21)
Lin, Z. C.
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Hsieh, W. H.
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Lee, C. P.
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Suen, Y. W.
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電子工程學系及電子研究所
Strong asymmetry of electron mobility in InGaAs/InAlAs heterostructures (lattice matched to InP) with the presence of InAs quantum wires was observed. Self-assembled InAs quantum wires, embedded in an InGaAs matrix close to the hetero-interface, has a strong effect in electron conduction in the interface channel. The low temperature mobility for electrons moving parallel to the quantum wires is much higher than that of electrons moving perpendicular to the wires. The asymmetry in mobility is attributed to the difference in scattering cross section of the quantum wires in these two directions.
Temperature dependence of the excess noise of a GaN nanowire device
(2007)
Li, L. C.
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Huang, S. Y.
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Wei, J. A.
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Suen, Y. W.
;
Lee, M. W.
We report on the study of the low-frequency excess noise of a GaN nanowire (NW) device from room temperature to 135 K. A Lorentzian noise is found to be embedded in the 1/f noise background, and becomes more significant as the bias current increases or the temperature decreases. The temperature dependance of the associated characteristic time, extracted from the spectrum, shows two thermally activated regions with different activation energies, which originate from different carrier-trapping levels in the NW device. The temperature dependence of the 1/f noise is difficult to unveil due to the presence of the strong Lorentzian noise.