Browsing by Author "Wang, YH"

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1.55-mu m and infrared-band photoresponsivity of a Schottky barrier porous silicon photodetector
(2001-02-01)
Lee, MK
;
Chu, CH
;
Wang, YH
;
Sze, SM
;
電子工程學系及電子研究所
We have investigated the spectral responsivity of porous silicon Schottky barrier photodetectors in the wavelength range 0.4-1.7 mum The photodetectors show strong photoresponsivity in both the visible and the infrared bands, especially at 1.55 mum. The photocurrent can reach 1.8 mA at a reverse bias of 6 V under illumination by a 1.55-mum, 10-mW laser diode. The corresponding quantum efficiency is 14.4%. (C) 2001 Optical Society of America.
A scalable noise de-embedding technique for on-wafer microwave device characterization
(2005-10-01)
Cho, MH
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Huang, GW
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Wang, YH
;
Wu, LK
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電信工程研究所
In this letter, we present a scalable and efficient noise de-embedding procedure, which is based on transmission-line theory and cascade configurations, for on-wafer microwave measurements of silicon MOSFETs. The proposed de-embedding procedure utilizes one open and one thru dummy structures to eliminate the parasitic effects from the probe pads and the input/output interconnects of a device-under-test (DUT), respectively. This method can generate the scalable distributed interconnect parameters to efficiently and precisely remove the redundant parasitics of the DUTs with various device sizes and arbitrary interconnect dimensions.
A shield-based three-port de-embedding method for microwave on-wafer characterization of deep-submicrometer silicon MOSFETs
(2005-09-01)
Cho, MH
;
Huang, GW
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Wu, LK
;
Chiu, CS
;
Wang, YH
A general three.-port S-parameter de-embedding method using shield-based test structures for microwave on-wafer characterization is presented in this paper. This method does not require any physical equivalent-circuit assumption for the surrounding parasitics of a device-under-test. We use one open and three thru dummy devices to remove the parasitic components connected to the gate, drain, and source terminals of a MOSFET. By shielding the lossy silicon substrate, the cross-coupling from port to port can be significantly mitigated, and thus, the parasitics of probe pads and interconnects at each port can be separately subtracted. The MOS transistor and its corresponding dummy structures fabricated in a 0.18-mu m CMOS process were characterized up to 20 GHz. Compared with the two-port cascade-based de-embedding method, the proposed three-port de-embedding procedure can further eliminate the parasitics associated with the dangling leg in the source terminal. The impacts of the accuracy of the de-embedding technique on device modeling and simulation are also discussed.
Effects of film stress on the chemical mechanical polishing process
(1999-11-01)
Tseng, WT
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Wang, YH
;
Chin, JH
;
機械工程學系
;
Department of Mechanical Engineering
A theoretical model is constructed to simulate the pressure distribution arising from wafer curvature (film stress) during chemical mechanical polishing (CMP), based on theories of elastic contact stress. Results from oxide CMP experiments suggest that the wafer curvature results in a nonuniform polish rate distribution across the wafer, in agreement with the simulation based on the model. This stress-dependent polish nonuniformity is attributed to the nonuniform pressure distribution across the wafer, induced by the wafer radius of curvature (film stress). Also, it was found that the magnitude of bride film stress itself has little effect on removal rate. Oxides with tensile stress tend to have a weakened bond structure and enhanced chemical reactivity, both of which result in slightly higher removal rates. The reverse is true for oxides with compressive stress. Deviations from the model prediction mag. result from the stress induced by slurry flow, local variations in wafer shape and form, and pad surface properties. (C) 1999 The Electrochemical Society. S0013-4651(99)03-063-3. All rights reserved.
Estimation of dynamic origin-destination by Gaussian state space model with unknown transition matrix
(2003)
Jou, YJ
;
Hwang, MC
;
Wang, YH
;
Chang, CH
;
統計學研究所
Dynamic origin-destination (O-D) pattern representing time-dependent trip demands from one place (origin) to another (destination) is one of the most essential input data for most traffic operational analyses. Historical studies assumed that the transition matrix is known or at least approximately known, which is unrealistic for a real world network. And due to the fact that the number of trips to a specific destination, y, is easy to obtain and the O-D variable, x (path flow based in this research), is not directly observable, a Gaussian state space model is formulated to describe the relationships of x and y, observation equations, and the dynamics of x, state equations with unknown transition matrix. Under the assumption of Gaussian noise terms in state space model, the distribution of random transition matrix F is derived. A solution algorithm combining Gibbs sampler and Kalman filter to tackle the problem of simultaneous estimation of F and x, based on the latest available information is proposed. Real O-D data from Taipei Rapid Transit is used to verify the presented model and solution method. Preliminary results are generally satisfactory, showing that also in the unknown transition matrix case, significant estimates are achieved.
Liquid phase deposited SiO2 on GaN
(2003-04-29)
Wu, HR
;
Lee, KW
;
Nian, TB
;
Chou, DW
;
Wu, JJH
An efficient and low cost approach to deposit uniform silicon dioxide layers on GaN by liquid phase deposition (LPD) near room temperature are described and discussed. The process is simple. GaN wafers are immersed into a H2SiF6 and H3BO3 solution to form the silicon dioxide layers. The deposition conditions and the properties of the SiO2 films will be characterized. (C) 2002 Elsevier Science B.V. All rights reserved.
Magneto-optic imaging of proton-irradiated high T-c superconducting thin films: A revisit of J(c)(T) functional and flux pinning enhancement
(2001-10-10)
Wang, C
;
Seo, HW
;
Su, CJ
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Wang, YH
;
Chen, QY
We have performed systematic quantitative measurements of the critical current density J(c)(B,T) for YBCO thin films proton-irradiated to various dosages using the MOI technique. Results for external magnetic fields up to 400Oe and temperature ranging from 5 to 80 K are T resented for a 600 nm thick YBCO film irradiated by proton up to a dosage of 10(16) cm(-2) at 500 keV. While no significant differences were observed for T > 50K, the J(c) values consistently increased with the increasing external field for T < 50 K.
Study of annealing and exchange bias effects in PtMn based magnetic tunnel junction system
(2004)
Peng, TY
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Yao, YD
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Chen, SY
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Wang, YH
;
Chen, WC
The crystallization structure and thickness of PtMn layer in a magnetic tunnel junction system are important factors to improve its exchange bias effect. This study shows that the PtMn layer could be changed from a FCC (111) structure to a FCT (111) structure after annealing above 270 degreesC. The minimum thickness of PtMn layer is found to be 10 nm for exchange coupling effect to be occurred in our MTJ system. The magnetic exchange effect between PtMn and SAF layers is near 4,300 Oe. Annealing temperatures can be higher than 400 degreesC for samples without patterning; however, temperature at 275 degreesC is too high for samples after patterning. This may be due to the breakdown of edges of the patterned samples as well as the complicated environments around the patterned samples. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Wafer bonding by Ni-induced crystallization of amorphous silicon
(2003-09-01)
Chao, CP
;
Wu, YCS
;
Lee, TL
;
Wang, YH
;
材料科學與工程學系
Wafer bonding by Ni-induced crystallization of amorphous silicon was investigated. It was found that wafers can be bonded through the crystallization of amorphous silicon at temperatures below 550 degreesC. Moreover, when 250 V was applied across the stacked samples, the bonding temperatures could be decreased to as low as 350 degreesC.