Browsing by Author "Wang, JC"

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A physical model for the hysteresis phenomenon of the ultrathin ZrO2 film
(2002-10-01)
Wang, JC
;
Chiao, SH
;
Lee, CL
;
Lei, TF
;
Lin, YM
This work studies and presents an inner-interface trapping physical model for the ultra-thin (effective oxide thickness=15 Angstrom) zirconium oxide (ZrO2) film to explain its hysteresis phenomenon. The shift of the capacitance-voltage characteristics swept from accumulation to inversion and then swept back with light illumination is about 110 mV, which is larger than the shift without light illumination (similar to45 mV). The mobile ion effect is obviated using bias-temperature stress measurement. The proposed model successfully explains not only the phenomenon but also the thickness effect for the capacitance-voltage characteristics and the different turn-around voltages of the current density-voltage characteristics of the zirconium dielectrics. (C) 2002 American Institute of Physics.
A weight-assessing method with habitual domains
(1998-10-16)
Tzeng, GH
;
Chen, TY
;
Wang, JC
;
管理學院
;
College of Management
Weights of criteria are the important factors in decision-making. However, from a behavioral perspective, traditional weighting methods account for too few factors to deal with decisions properly. Based on the behavior mechanism and the theory of habitual domains, this study is undertaken to develop a new weight-assessing model that treats decisionmaking as a dynamically adjusting process proceeding from the ideal to actual states. The new model is built upon the dynamic analysis for the connectivities between criteria instead of the static analysis of traditional models. Finally, we have studied Taipei City motorcycle users, mode-choice behavior through questionnaire in order to show the applicability of the new model. From the empirical results, it is found that our weight-assessing method has significant application potential in practice. (C) 1998 Elsevier Science B.V. All rights reserved.
Carrier transportation of rapid thermal annealed CeO2 gate dielectrics
(2004)
Wang, JC
;
Chiang, KC
;
Lei, TF
;
Lee, CL
;
電子工程學系及電子研究所
We investigated the carrier transportation of ultrathin CeO2 gate dielectrics with rapid thermal annealing (RTA). After annealing, the effective oxide thickness was decreased and the characteristics were significantly improved. Temperature dependence of gate leakage current was studied and Frenkel-Poole dominated the conduction mechanism for low RTA temperature. As the annealing temperature increases, Fowler-Nordheim tunneling became much more important and the CeO2/n-Si electron barrier height of 0.75 eV was extracted for future modeling and simulation. In addition, the energy band diagram of Al/CeO2/n-Si structure was established for the first time. (C) 2004 The Electrochemical Society.
Carrier-carrier scattering in GaAs/AlxGa1-xAs quantum wells
(2000-06-15)
Sun, KW
;
Song, TS
;
Sun, CK
;
Wang, JC
;
Kane, MG
We have studied carrier dynamics in highly nonequilibrium two-dimensional (2D) carrier distributions generated with femtosecond laser pulses in p-doped GaAs/Al0.32Ga0.68As quantum wells at photoexcited carrier densities between 10(9) and 10(11) cm(-2). The initially nonthermal carrier distribution is quickly broadened due to inelastic carrier-carrier scattering, with the broadening rate increasing as carrier density is increased. Measurements of the unrelaxed peak height in the hot electron-neutral acceptor luminescence spectra are compared with calculations of the carrier distribution using integration of the 2D dynamically screened Boltzmann equation. Our results indicate that carrier-carrier scattering becomes as significant a scattering mechanism as LO-phonon emission at density of about 10(10) cm(-2).
Carrier-carrier scattering: an experimental comparison of 5 and 3 nm AlxGa1-xAs/GaAs quantum wells
(2000)
Sun, KW
;
Sun, CK
;
Wang, JC
;
Wang, SY
;
Lee, CP
We have studied carrier dynamics among highly nonequilibrium carrier distributions generated with femtosecond laser pulses in Be:AlxGa1-xAs/GaAs quantum wells with different well width at hot carrier densities between 10(9) and 10(11) cm(-2). The spectra, at moderately high densities (greater than or equal to 10(10) cm(-2)) indicate that the initially narrow electron distribution is altered in a time less than or equal to the LO-phonon emission time, as a result of rapid carrier-carrier scattering. At an excitation density of about 10(10) cm(-2), the carrier-carrier scattering rate is faster in narrower quantum wells. By measuring the intensity of the unrelaxed peak, it is possible to determine the relative rates of carrier-carrier scattering and LO-phonon emission. Our results indicate that carrier-carrier scattering becomes as significant as LO-phonon emission at a density of about 1 x 10(10) cm(-2) in the 5 nm quantum wells. (C) 2000 Elsevier Science Ltd. All rights reserved.
Characteristics improvement and carrier transportation of CeO2 gate dielectrics with rapid thermal annealing
(2004)
Wang, JC
;
Chiang, KC
;
Lei, TF
;
Lee, CL
;
電子工程學系及電子研究所
In this paper, we have investigated the properties and carrier transportation of ultra-thin cerium dioxide films with rapid thermal annealing. Improved characteristics such as low leakage current, high breakdown voltage and large time-dependent-dielectric-breakdown (TDDB) are obtained owing to the more stoichiometric of the CeO2 films after high temperature annealing. Moreover, temperature dependence of gate leakage current under substrate injection is studied, and the carrier conduction mechanisms, including the Frenkel-Poole (F-P) conduction and the Fowler-Nordheim (F-N) tunneling are also proposed, from which we have deduced the energy band diagram of Al/CeO2/n-Si structure for the first time.
Characteristics of fluorine implantation for HfO2 gate dielectrics with high-temperature postdeposition annealing
(2006-04-01)
Lai, CS
;
Wu, WC
;
Wang, JC
;
Cha, TS
;
物理研究所
In this work, we describe the characteristics of silicon surface fluorine implantation (SSFI) for HFO2 films with high-temperature postdeposition annealing. The thermal stability of HfO2 gate dielectrics is much improved owing to the incorporation of fluorine into HfO2 thin films. The gate leakage current of the SSFI HfO2 films is about three orders less than that of samples without any fluorine implantation. In addition, improvements in stress-induced leakage current (SILC) and charge trapping characteristics are realized in the HfO2 films with the SSFI. The incorporation of fluorine atoms into the HfO2 films reduces not only interface dangling bonds but also bulk traps, which is responsible for the improvements in properties.
Characterization of CF4-plasma fluorinated HfO2 gate dielectrics with TaN metal gate
(2005-05-30)
Lai, CS
;
Wu, WC
;
Wang, JC
;
Chao, T
;
物理研究所
In this paper, fluorine incorporation into the HfO2 gate dielectrics by post CF4 plasma treatment was proposed to improve the electrical characterization. TaN-HfO2-p-Si capacitors were demonstrated in this work. The characteristics of fluorinated HfO2 gate dielectrics were improved, including the capacitance-voltage hysteresis and current-voltage behaviors. This may be attributed to the fluorine incorporated into the HfO2 gate dielectrics as revealed by secondary ion mass spectroscopy. Moreover, the formation of Hf-F bonding was observed through electron spectroscopy for chemical analysis spectra. (c) 2005 American Institute of Physics.
Characterization of temperature dependence for HfO2 gate dielectrics treated in NH3 plasma
(2003-10-01)
Wang, JC
;
Shie, DC
;
Lei, TF
;
Lee, CL
;
電子工程學系及電子研究所
For the first time, the characteristics and temperature dependence of electrical properties for ultrathin HfO2 gate dielectrics treated in NH3 plasma after deposition were investigated. After this treatment, significant nitrogen incorporation at the HfO2/silicon interface (interfacial layer) was examined by Auger electron spectroscopy. Moreover, the formation of Hf-N bonding and the suppression of Hf-Si bonding were observed from electron spectroscopy for chemical analysis spectra. The activation energy of charge trapping reflected in the current-voltage characteristics was effectively reduced, which led to improved hysteresis and its weaker temperature dependence in HfO2 gate dielectrics treated in NH3 plasma. (C) 2003 The Electrochemical Society.
Effects of post CF(4) plasma treatment on the HfO(2) thin film
(2005-04-01)
Lai, CS
;
Wu, WC
;
Fan, KM
;
Wang, JC
;
Lin, SJ
In this study, a novel approach was proposed to improve the characterization of HfO(2). Fluorine was incorporated by CF(4) plasma to improve the HfO(2) gate dielectric properties including leakage current, breakdown voltage and hysteresis. The hysteresis of capacitance-voltage characteristics can be reduced to approximately 10% hysteresis voltage for the samples with CF(4) plasma treatment. An inner-interface trapping model is presented to explain the hysteresis. The secondary-ion mass spectroscopy (SIMS) results show that there is a significant incorporation of fluorine (F) at the interface between the HfO(2) thin film and silicon substrate. The incorporation of F effectively suppressed leakage current and improved carrier trapping without an increase in interfacial layer thickness.
Efficient key distribution schemes for secure media delivery in pay-TV systems
(2004-10-01)
Huang, YL
;
Shieh, S
;
Ho, FS
;
Wang, JC
;
資訊工程學系
To provide secure media delivery in pay-TV systems, a large number of messages are exchanged for key updates in the conventional key distribution schemes. This is inefficient and costly when the client side (set-top box) uses a smart card with limited computing power. In this paper, we present three key distribution schemes for channel protection and secure media delivery in pay-TV systems. With the proposed schemes, encryption keys of the subscribed programs can be efficiently and securely distributed to the authorized subscribers. Only one message is needed to renew key in the key distribution schemes for subscription channel protection. In addition, we use simpler computation functions, including one-way hash function and exclusive-OR operation, for key updates to reduce the computation cost. With our key distribution schemes, only authorized subscribers can watch the subscribed programs correctly. Unauthorized subscribers have no information to retrieve the correct programs over the networks. Thus, service providers can charge their subscribers according to their subscriptions, and the illegal access of the media and video programs from networks can be prevented, based on the proposed schemes.
High reliability ultrathin interpolyoxynitride dielectrics prepared by N2O plasma annealing
(2003-12-01)
Wang, JC
;
Lee, JW
;
Kuo, LT
;
Lei, TF
;
Lee, CL
This work addresses the preparation of ultrathin (effective oxide thickness, 42 Angstrom) interpoly-oxynitride (SiOxNy) films by annealing thin nitride films with high density N2O plasma and N2O rapid thermal annealing. The proposed oxynitride dielectrics formed using N2O plasma annealing exhibited low gate leakage current, high breakdown electric field, long ten-year lifetime, and large effective barrier height. These superior properties can be attributed to the high concentration of oxygen incorporated in the poly-II/nitride interface and a reduction of the trap density of the interpoly-oxynitride films. The dielectric is a suitable substitute for the inter-polyoxide of electrically-erasable programmable read only memory. (C) 2003 The Electrochemical Society.
Identification of general fuzzy measures by genetic algorithms based on partial information
(2000-08-01)
Chen, TY
;
Wang, JC
;
Tzeng, GH
;
管理學院
;
College of Management
This study develops an identification procedure for general fuzzy measures using genetic algorithms, In view of the difficulty in data collection in practice, the amount of input data is simplified through a sampling procedure concerning attribute subsets, and the corresponding detail design is adapted to the partial information acquired by the procedure. A specially designed genetic algorithm is proposed for better identification, including the development of the initialization procedure, fitness function, and three genetic operations. To show the applicability of the proposed method, this study simulates a set of experimental data that are representative of several typical classes. The experimental analysis indicates that using genetic algorithms to determine general fuzzy measures can obtain satisfactory results under the framework of partial information.
Improved characteristics of ultrathin CeO2 by using postnitridation annealing
(2004-02-01)
Wang, JC
;
Hung, YP
;
Lee, CL
;
Lei, TF
;
電子工程學系及電子研究所
This work demonstrates the improved characteristics of an ultrathin CeO2 dielectric by using the post-N2O plasma treatment with additional rapid thermal N-2 annealing. The CeO2 after the treatment exhibits superior characteristics such as a small effective oxide thickness (similar to2.25 nm), a low leakage current (5.4 x 10(-4) A/cm(2)), a high breakdown electric field (-24 MV/cm), a long projected 10 yr lifetime (-12 MV/cm), a small capacitance-voltage hysteresis (25 mV), and a high barrier height for Frenkel-Poole emission (0.55 eV). These good properties are attributed to the nitrogen incorporation into the dielectric to eliminate the traps after annealing. The postnitridation annealing appears to be a very useful treatment for future ultrathin metal-oxide gate dielectrics. (C) 2004 The Electrochemical Society.
Practical key distribution schemes for channel protection
(2000)
Huang, YL
;
Shieh, SPW
;
Wang, JC
;
資訊工程學系
;
Department of Computer Science
This paper presents three key distribution schemes for channel protection. With the proposed schemes, encryption keys of the ordered programs can be distributed to the authorized subscribers efficiently and securely. In these schemes, for key updates, at most two messages are transmitted and simpler computation functions, including one-way hash function and XOR operation, are used to reduce the computation cost compared to existing solutions. With our key distribution schemes, only the authorized subscribers can decrypt the ordered programs. Thus, the service provider in a Pay-TV system can charge his subscribers according to their subscriptions and the intelligent property rights of TV programs can be protected by the proposed schemes.
Soft breakdown of hafnium oxynitride gate dielectrics
(2005-07-15)
Wang, JC
;
Shie, DC
;
Lei, TF
;
Lee, CL
;
電子工程學系及電子研究所
A detailed study of soft breakdown modes for hafnium oxynitride (HfON) gate dielectrics under stress is investigated. Two types of soft breakdown, digital and analog modes, are observed in HfON gate dielectrics, featuring gate voltage fluctuation accompanying random telegraph noise and nonswitching 1/f noise, respectively. The dependence of gate area, oxide thickness, and stress current density on breakdown modes is also studied. Thin oxide thickness and small gate area contribute to the enhancement of charge to breakdown (Q(bd)). Large Joule heat damage generated under stress inducing the analog soft breakdown for thick hafnium oxynitride films is proposed to clearly understand the breakdown of HfON gate dielectrics. (c) 2005 American Institute of Physics.
Temperature dependence of vortex configuration by honeycomb hole arrays in a superconducting Nb film
(2005-05-15)
Wu, TC
;
Wang, JC
;
Horng, L
;
Wu, JC
;
Yang, TJ
A honeycomb array of submicrometer holes in a Nb superconducting thin film has been fabricated to investigate the flux pinning effect. It is found that the minima positions reveal two regimes characterized by the matching fields and the fractional ones. It is believed that the complex behavior may come from more than one vortex being captured per pinning site. Furthermore, the temperature dependence of the saturation number of vortices per pinning site together with vortex-vortex interaction gives the complex vortex configurations. (c) 2005 American Institute of Physics.
Turnaround of hysterisis for capacitance-voltage characteristics of hafnium oxynitride dielectrics
(2004-03-01)
Wang, JC
;
Shie, DC
;
Lei, TF
;
Lee, CL
;
電子工程學系及電子研究所
The capacitance-voltage (C-V) characteristics of hafnium oxynitride gate dielectrics for silicon metal-oxide-semiconductor (MOS) capacitors with different sweep voltage were investigated. It was found that, for the p-type substrate MOS capacitor, the C-V hysterisis has a turnaround characteristic as the applied voltage exceeds -3.0 V. The phenomenon is explained by electron trappings at the low electric field and hole trappings, which resulted from the impact ionization, at the high electric field in the dielectrics. (C) 2004 American Institute of Physics.
Ultrafast carrier-carrier scattering in AlxGa1-xAs/GaAs quantum wells
(1999-12-01)
Sun, KW
;
Song, TS
;
Sun, CK
;
Wang, JC
;
Wang, SY
We present new time-resolved measurements that demonstrate the effect of injected carrier densities on carrier-carrier scattering rates of a highly nonequilibrium carrier distribution in the p-doped Al0.32Ga0.68As/GaAs quantum wells. The initially photoexcited nonthermal carrier distribution is quickly broadened due to rapid increase of the inelastic carrier-carrier scattering as the injected carrier densities increased toward 10(11) cm(-2). (C) 1999 Elsevier Science B.V. All rights reserved.