J.F. Chen

Publications (135)180.97 Total impact

• Source

  Available from: ucsb.edu

  Article: Grain-Orientation Induced Quantum Confinement Variation in FinFETs and Multi-Gate Ultra-Thin Body CMOS Devices and Implications for Digital Design

  S.H. Rasouli, K. Endo, J.F. Chen, N. Singh, K. Banerjee
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  ABSTRACT: This paper identifies and investigates a new source of random threshold voltage variation, which is referred to as Grain-Orientation-induced Quantum Confinement (GOQC) in emerging ultra-thin-body metal-gate complementary metal-oxide-semiconductor (CMOS) devices including FinFET, tri-gate, and nanowire field-effect transistors. Due to the dependence of the work function of the metal gates on their grain orientations, different parts of the gate in multigate CMOS devices can have different work functions, resulting in a high electric field in the channel (body) of these devices and, hence, in electrical confinement of the carriers. GOQC effect is shown to be the dominant source of the quantum threshold voltage variation in all emerging ultra-thin multi-gate devices including FinFETs. It is also highlighted for the first time that such variations can have significant implications for the performance and reliability of minimum-sized digital circuits such as static random-access memory cells.
  IEEE Transactions on Electron Devices 09/2011; · 2.32 Impact Factor
• Article: Analysis of GIDL-Induced off-State Breakdown in High-Voltage Depletion-Mode nMOSFETs

  J.F. Chen, Chin-Rung Yan, Yin-Chia Lin, Jhen-Jhih Fan, Sheng-Fu Yang, Wen-Chieh Shih
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  ABSTRACT: A gate-induced-drain-leakage-induced off-state breakdown is examined in our high-voltage depletion-mode n-channel metal-oxide-semiconductor field-effect transistors. By increasing the dosage in the n-region, a bell-shaped trend between the off-state breakdown voltage and the dosage in the n-region is observed. Such a bell-shaped trend is found to result from two competing factors: an electric field in the gate edge and an electric field associated with the drain-bulk junction. The latter electric field is responsible for the falling part in the bell-shaped trend. Our model can explain the data of the slightly bell-shaped trend between off-state and implant energy in the n-region. Additionally, the effect of Si recess variation on off-state variation can be understood from our model. According to our model, approaches to improve off-state and the effect of Si recess variation on variation are proposed.
  IEEE Transactions on Electron Devices 07/2011; · 2.32 Impact Factor
• Article: Capacitor energising transient limiter for mitigating capacitor switch-on transients

  S.-T. Tseng, J.-F. Chen
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  ABSTRACT: Capacitors are prone to two major types of energising transient phenomenon: transient overvoltage and inrush current (charging current). Energising transients will shorten the lifetime of the capacitor, and furthermore they will damage the contacts of the switching device. This study proposes a rectifier type capacitor energising transient limiter (CETL) for mitigating the isolated capacitor and back-to-back capacitor switch-on transients. The operating condition of the proposed circuit can be divided into two states: the charging suppressive mode and the steady state with its initial transient. During the charging suppressive mode, a pair of diode strings conducts automatically and then the DC reactor provides high impedance at the instant of switching on in order to suppress the capacitor energising transients. During the steady state with its initial transient, all diodes of the bridge rectifier conduct simultaneously and the limiter freewheels; therefore the limiter acts as a short circuit and has no effect. Thus, it is not necessary to increase the capacitor-rated voltage when the CETL is used. In this study, experiments and simulations are carried out to demonstrate the feasibility of the proposed limiter circuit.
  IET Electric Power Applications 04/2011; · 1.17 Impact Factor
• Article: Digital-signal-processor-based DC/AC inverter with integral-compensation terminal sliding-mode control

  F.-J. Chang, E.-C. Chang, T.-J. Liang, J.-F. Chen
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  ABSTRACT: Classic terminal sliding-mode control (TSMC) has finite system-state convergence time and is robust against system disturbances and uncertainties, but TSMC may suffer from steady-state error problems under disturbed-system conditions. This study proposes to improve the performance of TSMC by the addition of integral compensation, which eliminates steady-state errors in the DC/AC inverter. Thus, the proposed controller provides robust performance in controlling the DC/AC inverter output to track the sinusoidal reference at steady state, and also provides fast response under varying load conditions. A real-time digital-signal-processor-based laboratory prototype is implemented to confirm the theoretical analysis and effectiveness of the proposed controller.
  IET Power Electronics 02/2011; · 1.62 Impact Factor
• Conference Proceeding: Characterizations of Nb2O5 modified PZT piezoelectric ceramics and feasibility study for acoustic sensor

  Bing-Huei Chen, Long Wu, Jia-Bin Wang, Ching-Chou Su, C.C. Tai, J.F. Chen
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  ABSTRACT: The aim of this report is to improve piezoelectric properties of Pb(Zr,Ti)O₃ ceramics with a composition Zr/Ti=53/47 prepared by the conventional ceramic technology through a simple, yet effective method by addition of 1 mole% Nb-doped as a donor element. Replacement of Ti⁺⁴ by Nb⁺⁵ in such perovskite type solid solutions was accomplished by the creation of cation vacancies. The dependence of sintering effects on microstructure and ferroelectric characteristics were surveyed. From the analysis results, the PZT bulk ceramic grains distribution were found to be uniform, the sample was found to possess well-piezoelectric properties. Calcined at 850°C/2h and sintered at 1280°C/2h, the PZT ceramics had the minimum value of dielectric loss D=0.0151, mechanical quality factor Q_m=105 and exhibited maximum electromechanical coupling factor k_p=0.65. It was noted that the fundamental resonance frequency was around 200 KHz. Through the analyses of the study, we found an extremely good processing conditions and obtained well-performed piezoelectric properties and piezoelectric response suitable for piezoelectric applications, like resonator, actuator, sensor, filter et al. These in turn can serve as detecting devices with a wide range of was also evaluated. Finally, an acoustic sensor developing for non-destructive application would be our major issue for further investigation.
  Piezoelectricity, Acoustic Waves and Device Applications (SPAWDA), 2010 Symposium on; 01/2011
• Article: Tunable erbium-doped fiber ring laser with signal-averaging function for fiber-optic sensing applications

  S. T. Kuo, P. C. Peng, M. S. Kao, H. H. Lu, J. F. Chen
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  ABSTRACT: This work proposes a novel erbium-doped fiber ring laser as a sensing control center (CC) for long-haul fiber Bragg grating (FBG) sensor systems. The tunable erbium-doped fiber laser with signal averaging functionality not only provides intense and stable laser light, but also suppresses the effect of noise on the system performance. A sample 30/60 km FBG sensor array is connected to the fiber ring laser to demonstrate experimentally the feasibility and effectiveness of the laser as a CC. The experimental results indicate that the signal averaging operation inside the proposed setup increases the system signal-to-noise ratio (SNR).
  Laser Physics - LASER PHYS. 01/2011; 21(1):188-190.
• Conference Proceeding: An isolated high step-up forward/flyback active-clamp converter with output voltage lift

  P.H. Kuo, T.J. Liang, K.C. Tseng, J.F. Chen, S.M. Chen
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  ABSTRACT: This paper presents an isolated high step-up forward/flyback active-clamp converter with output voltage lift. In order to obtain high step-up voltage gain, the output voltage lift is adopted. The characteristics of the output voltage lift are similar to the forward converter in the charging mode and the flyback converter in the discharging mode. The active-clamp circuit is employed to recycle the leakage-inductance energy of the forward/flyback transformer and to suppress the voltage stress on the switch. By utilizing the active-clamp circuit, both primary and auxiliary switches can achieve zero-voltage-switching (ZVS), thus improving the efficiency of the proposed converter. Finally, a prototype circuit with 24-V input voltage, 200-V output voltage, and 400-W output power is implemented to verify the performance.
  Energy Conversion Congress and Exposition (ECCE), 2010 IEEE; 10/2010
• Article: Bimodel onset strain relaxation in InAs quantum dots with an InGaAs capping layer

  J. F. Chen, Ross C. C. Chen, C. H. Chiang, Y. F. Chen, Y. H. Wu, L. Chang
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  ABSTRACT: Capping InAs quantum dots (QDs) with an InGaAs layer allows strain relaxation to induce a low-energy electron state below a set of fine dot family states, which is consistent with photoluminescence (PL) spectra. The evolution of InAs thickness suggests a bimodal onset relaxation, i.e., a fine dot family that is strain-relieved by indium outdiffusion from the QDs, as suggested by transmission electron microscopy, and a low-energy dot family that is strain relaxed by the generation of lattice misfits. The indium outdiffusion can explain an abnormal PL blueshift in 70 meV in the fine dot family at onset of strain relaxation.
  Applied Physics Letters 09/2010; 97(9):092110-092110-3. · 3.84 Impact Factor
• Article: Modified PWM switch model for continuous conduction mode DC-DC converters with coupled inductors

  C.-Y. Chang, W.-S. Liu, J.-F. Chen, R.-L. Lin, T.-J. Liang, M.-H. Chen
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  ABSTRACT: A modified PWM switch model for DC-DC converters operating in continuous conduction mode (CCM) is proposed in this study. The modified model is based on the conventional PWM switch model. Compared to other modelling methods, the conventional model is versatile and easy to implement. However, it is typically restricted to a few topologies only. Therefore in this study, the proposed modified model expands the application fields, which includes the DC-DC converter with the coupled inductor; it can also be used in basic converters as a conventional topology. A high step-up buck-boost converter was built for this investigation to verify the accuracy of the modified model. The experimental results show that this modified model can accurately predict the characteristics of the system.
  IET Power Electronics 08/2010; · 1.62 Impact Factor
• Article: Step-up DC-DC converter by coupled inductor and voltage-lift technique

  S.-K. Changchien, T.-J. Liang, J.-F. Chen, L.-S. Yang
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  ABSTRACT: A DC-DC converter with high step-up voltage gain is presented. The proposed converter uses the coupled inductor and the voltage-lift technique to achieve high step-up voltage gain. Additionally, the voltage on the active switch is clamped, and the energy stored in the leakage inductor is recycled in the proposed converter. Therefore the voltage stress on the active switch is reduced, and the conversion efficiency is improved. Finally, a laboratory prototype circuit with input voltage 12-V, output voltage 100-V and output power 35-W is implemented to demonstrate the performance of the proposed converter.
  IET Power Electronics 06/2010; · 1.62 Impact Factor
• Article: Improvement of Poly-Pimple-Induced Device Mismatch on 6T-SRAM at 65-nm CMOS Technology

  Chan-Yuan Hu, J.F. Chen, Shih-Chih Chen, Shoou-Jinn Chang, Kay-Ming Lee, Chih-Ping Lee
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  ABSTRACT: An incremental poly etching method can improve the poly pimple defect-induced device mismatch on the static noise margin (SNM) of 65-nm-node low-power 6T-SRAM. The improvement on circuit level is examined by the yield of scan chain and memory built-in self-test (MBIST), which is known to correlate well to process-induced defects.
  IEEE Transactions on Electron Devices 05/2010; · 2.32 Impact Factor
• Article: Mechanisms of Hot-Carrier-Induced Threshold-Voltage Shift in High-Voltage p-Type LDMOS Transistors

  J.F. Chen, Kuen-Shiuan Tian, Shiang-Yu Chen, Kuo-Ming Wu, J.R. Shih, K. Wu
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  ABSTRACT: The phenomena and mechanisms of hot-carrier-induced threshold-voltage ( V _T) shift in high-voltage p-type laterally diffused MOS (LDMOS) transistors are investigated. At low-| V _gs| (absolute value of gate voltage) stress condition, electrons are injected and trapped in the gate oxide at the channel region near the drain, resulting in V _T increase (Delta|V_T| < 0). At high-| V _gs| stress condition, however, severe V _T decrease (Delta|V_T| > 0) is found after stress. Experimental results suggest that donor-type interface traps created by hole injection in the channel region is the dominant factor for V _T decrease.
  IEEE Transactions on Electron Devices 01/2010; · 2.32 Impact Factor
• Article: Convergence of Hot-Carrier-Induced Saturation Region Drain Current and On-Resistance Degradation in Drain Extended MOS Transistors

  J.F. Chen, Shiang-Yu Chen, Kuo-Ming Wu, J.R. Shih, Kenneth Wu
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  ABSTRACT: Hot-carrier-induced device degradation in n-type high-voltage drain-extended MOS (DEMOS) devices stressed under high drain voltage and high gate voltage ( Vg ) is investigated. Charge pumping data and technology computer-aided-design simulation results reveal that hot-carrier-induced interface state formation in the gate overlapped shallow trench isolation region is responsible for device degradation. Furthermore, an unexpected high saturation region drain current ( Id (sat)) degradation (close to on-resistance degradation) is observed. The occurrence of quasi-saturation under high Vg bias is the cause of significant Id (sat) degradation. The results presented in this paper suggest that severe Id (sat) degradation may become a reliability concern for devices exhibiting the quasi-saturation phenomenon.
  IEEE Transactions on Electron Devices 12/2009; · 2.32 Impact Factor
• Source

  Available from: edu.tw

  Article: An Investigation on Anomalous Hot-Carrier-Induced On-Resistance Reduction in n-Type LDMOS Transistors

  J.F. Chen, Kuen-Shiuan Tian, Shiang-Yu Chen, Kuo-Ming Wu, J.R. Shih, K. Wu
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  ABSTRACT: In this paper, on-resistance ( R _on) degradation induced by hot-carrier injection in n-type lateral diffused metal-oxide-semiconductor transistors with shallow trench isolation (STI) in the drift region is investigated. R _on unexpectedly decreases under medium- and high-gate voltage ( V _gs) stress conditions. According to experimental data and technology computer-aided-design simulation results, the mechanisms responsible for anomalous R _on shift are proposed. When the device is stressed under medium V _gs, hot-hole injection and trapping occur at the STI edge closest to the channel, resulting in R _on reduction. Interface trap generation (?? N _it) occurs at the STI edge closest to the channel and nearby drift region, leading to R _on increase. For the device stressed under high V _gs, R _on reduction is also attributed to hole trapping at the STI corner closest to the channel. ?? N _it created by hot-electron injection at the STI edge closest to the drain dominates device characteristics and leads to R _on increase eventually. Based on the proposed R _on degradation mechanisms, an R _on degradation model is discussed and verified with experimental data.
  IEEE Transactions on Device and Materials Reliability 10/2009; · 1.54 Impact Factor
• Conference Proceeding: Effect of NDD dosage on hot-carrier reliability in DMOS transistors

  J.F. Chen, Kuen-Shiuan Tian, Shiang-Yu Chen, Kuo-Ming Wu, C.M. Liu
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  ABSTRACT: The hot-carrier reliability of high-voltage n-channel DMOS transistors with various dosage of n-type double diffusion (NDD) implant is investigated. Higher NDD dosage results in higher substrate current, however, on-resistance (Ron) degradation is lower. TCAD simulation suggests that hot-hole injection and trapping is responsible for this unexpected lower Ron degradation.
  Quality of Electronic Design, 2009. ISQED 2009. Quality Electronic Design; 04/2009
• Article: Influence of thermal annealing on the electron emission of InAs quantum dots containing a misfit defect state

  J. F. Chen, C. H. Yang, R. M. Hsu, U. S. Wang
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  ABSTRACT: We have investigated the effect of postgrowth thermal annealing on the electron emission from InAs quantum dots (QDs) containing a misfit-related defect state induced by strain relaxation. Additional carrier depletion in the GaAs bottom layer near the QD, caused by the defect state, can effectively suppress electron tunneling from the QD, leading to the observation of a thermal emission from the QD electron ground state to the GaAs conduction band with a large emission energy of 213 meV, in contrast to defect-free nonrelaxed QDs in which an emission of 58 meV from the QD electron ground state to first excited state is observed. The emission energy is reduced to 193 meV and to 164 meV after annealing at 650 and 700 ° C for 1 min, respectively. This emission energy reduction is correlated with the photoluminescence blueshift which is attributed to the interdiffusion of atoms across the QD interface. The electron emission from the QD first excited and ground states is found to be a thermal emission at high temperatures and a tunneling emission at low temperatures. The tunneling energy barrier is found to be comparable to the thermal emission energy, supporting a thermal emission to the GaAs conduction band. This study illustrates a significant effect of a defect state on the electron-emission process in the QDs, suggesting the possibility of modifying the electron emission time of the QDs by purposely introducing a deep defect state.
  Journal of Applied Physics 04/2009; · 2.17 Impact Factor
• Article: Strain relaxation in InAs self-assembled quantum dots induced by a high N incorporation

  J. F. Chen, C. H. Yang, Y. H. Wu, L. Chang, J. Y. Chi
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  ABSTRACT: The effect of a high N incorporation in self-assembled InAs quantum dots (QDs) is investigated by analyzing the electronic and structural properties around QD region. Capacitance-voltage profiling and admittance spectroscopy shows that N incorporation into the InAs QD layer leads to drastic carrier depletion in the QD layer and neighboring GaAs layers due to the formation of a deep defect state at 0.34–0.41 eV. The signature of this defect state is similar to those defects observed in strain relaxed QDs or InGaAs/GaAs quantum wells when the InAs deposition thickness exceeds a critical thickness. Accordingly, the N incorporation might result in strain relaxation either by increasing localized strain or by inducing composition inhomogeneities, which provide nucleation sources for strain relaxation. The argument of strain relaxation is supported by transmission electron microscopy that reveals lattice misfits at the QD layer and neighboring GaAs layers.
  Journal of Applied Physics 12/2008; · 2.17 Impact Factor
• Conference Proceeding: Digital and analog hybrid control of multiphase power modules with low output-voltage and high output-current

  C.Y. Yeh, L.S. Yang, T.J. Liang, R.L. Lin, J.F. Chen, H.T. Yang
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  ABSTRACT: In this paper, a digital and analog hybrid control of multiphase power-modules with low output-voltage and high output-current are presented. The topology of each power module is a current-fed push-pull converter. The front stage is a buck converter which is used to regulate the output voltage and the rear stage is a push-pull converter with the electrical isolation and voltage step-down function. The advantages of the hybrid controllers are fast load transient response, flexible control, high reliability, and high power density. Finally, three paralleled power-modules with 2.5 V/150 A output is implemented. Experimental results show that good output-voltage regulation, current-balance, and high efficiency can be achieved.
  Electrical Machines and Systems, 2008. ICEMS 2008. International Conference on; 11/2008
• Conference Proceeding: Fuel cell and battery hybrid supplied power system

  W.T. Yan, L.S. Yang, C.M. Hong, T.J. Liang, J.F. Chen, H.T. Yang
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  ABSTRACT: In this paper, a hybrid power system supplied by a fuel cell and a lead-acid battery is realized by using the digital signal processor (DSP) TMS320LF2407 for power management and interleaved control. When the power provided from the fuel cell is higher than the load power, the extra energy may be used to charge the lead-acid battery. When the fuel cell can not provide enough energy to the load, the shortage of energy will be supplied by the lead-acid battery. Experimental results show that the system operating modes can be changed automatically, and that the output voltage is regulated well during load variations. Also, high system efficiency is achieved.
  Electrical Machines and Systems, 2008. ICEMS 2008. International Conference on; 11/2008
• Source

  Available from: ncku.edu.tw

  Article: On-Resistance Degradation Induced by Hot-Carrier Injection in LDMOS Transistors With STI in the Drift Region

  J.F. Chen, Kuen-Shiuan Tian, Shiang-Yu Chen, Kuo-Ming Wu, C.M. Liu
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  ABSTRACT: In this letter, on-resistance ( R _on) degradation induced by hot-carrier injection in n-type lateral DMOS transistors with shallow-trench isolation (STI) in the drift region is investigated. R _on decreases at the beginning of stress, but R _on increases as the stress time is increased. Experimental data and technology computer-aided-design simulation results reveal that hot-hole injection and trapping at the STI corner closest to the channel are responsible for the R _on reduction. The damage caused by hot-electron injection at the STI edge closest to the drain is responsible for the R _on increase.
  IEEE Electron Device Letters 10/2008; · 2.85 Impact Factor