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179 results on '"Wen, Shi-Jie"'

1. Excess noise and thermoelectric effect in magnetron-sputtered VO2 thin films.

Author

Gunes, Ozan, Onumonu, Onyebuchi I., Gholizadeh, A. Baset, Zhang, Chunzi, Yang, Qiaoqin, Wen, Shi-Jie, Curry, Richard J., Johanson, Robert E., and Kasap, Safa O.

Subjects
THERMOELECTRIC effects, THIN films, SEEBECK coefficient, PINK noise, CURRENT fluctuations, PERCOLATION theory, NOISE
Abstract

This work presents the excess noise and thermoelectric (Seebeck) measurements on polycrystalline vanadium dioxide (VO2) thin films. Noise spectral power density (SPD) of current fluctuations in the semiconducting (SC) phase had a typical flicker noise (f−γ) characteristic with an average slope parameter γ of 1.13. Normalized SPD (Sn) values obtained in the SC-phase indicate that the noise originates in the bulk of the film. On the contrary, in the metallic (M)-phase, γ values were greater than unity, and the observed Sn values indicated that the origin of the noise is most likely from the contacts or surface rather than the bulk. A general decrease was observed in Sn by a factor of 4–5 from the SC- to M-phase. Moreover, Sn in the SC-phase showed no temperature dependence. An interpretation based on the number of charge carrier fluctuations in Hooge's model led to an unrealistically high Hooge parameter and had to be ruled out. We propose that the fluctuations are related to the mobility fluctuations of carriers arising primarily from grain-boundary scattering which explains the observed characteristics well. The Seebeck coefficients (S) obtained under both heating and cooling schedules showed the n-type nature of magnetron-sputtered VO2 films in the SC-phase. Differently, in the M-phase, the S value was positive. The S values obtained from the cooling schedule signified the low percolation threshold of the metal-to-insulator transition already demonstrated for VO2 thin films grown on r-cut sapphire using the Efros–Shklovskii percolation model. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Temperature Dependence of Critical Charge and Collected Charge in 5-nm FinFET SRAM

Author

Pieper, Nicholas J., Xiong, Yoni, Pasternak, John, Fung, Rita, Wen, Shi-Jie, Ball, Dennis R., and Bhuva, Bharat L.

Abstract

Single-port (SP) and two-port (TP) static random access memory (SRAM) arrays in a commercial 5-nm FinFET technology were exposed to alpha particles at ambient and elevated temperatures up to 100 °C. Results show that increasing operating temperatures of these devices leads to significant changes in single-event upset (SEU) cross sections and multicell upset rates. Technology computer-aided design (TCAD) simulations are used to investigate the changes in charge collection and its relationship with changes in restoring current to affect storage node susceptibility. Simulations show that diffusion charge collection increases significantly for low LET particles incident outside drain regions of storage nodes. However, increasing drive current with temperature for FinFET transistors leads to decreasing SEU cross section for temperatures rising from 25 °C to 75 °C. Differences in charge collection and capacitance between SP and TP cell designs lead to decreasing SEU cross section for SP cells and increasing cross section for TP cells as temperature increases to 100 °C. These changes in vulnerability may lead to inaccurate predictions from accelerated testing at ambient temperatures if real operational temperatures are different.

Published
2024
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14. Single-Event Upset Cross Section at High Frequencies for RHBD Flip-Flop Designs at the 5-nm Bulk FinFET Node

Author

Xiong, Yoni, Pieper, Nicholas J., Qian, Ying, Wodzro, Stuart E., Narasimham, Balaji, Fung, Rita, Wen, Shi-Jie, and Bhuva, Bharat L.

Abstract

Rapid advancements in semiconductor technologies have enabled circuit operation at gigahertz (GHz) frequencies. However, conventional radiation hardening by design (RHBD) methods may encounter challenges in the GHz frequency domain, leading to increased single-event upset (SEU) rates. In this study, the SEU susceptibility of flip-flop (FF) designs in a 5-nm bulk FinFET technology node, both with and without hardening techniques, operating at frequencies up to 0.7 GHz are assessed. Comprehensive experiments involving heavy-ion and alpha particles were conducted across a wide range of supply voltages and frequencies to investigate the SEU cross sections. Results demonstrate the relationship between SEU cross section, operating frequency, and particle linear energy transfer (LET) values for FF designs employing temporal and spatial hardening techniques. Notably, all hardened designs examined in this work exhibit significantly higher SEU cross sections when operating at 0.7 GHz compared to 2.5 MHz, approaching or surpassing the SEU cross section of an unhardened conventional D-FF. These findings underscore the significance of considering high-frequency and dynamic operational data, as relying solely on static or low-frequency information can lead to a substantial underestimation of SEU cross sections, thereby elevating failure rates in deployed electronic systems.

Published
2024
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22. Impact of CnRx Structure on Soft Error Rates of Flip-Flop Designs at 22-nm FD SOI Node

Author

Elash, Christopher J., Li, Zongru, Jin, Chen, Chen, Li, Wen, Shi-Jie, Fung, Rita, Xing, Jiesi, Shi, Shuting, Yang, Zhi Wu, and Bhuva, Bharat L.

Abstract

Embedded Silicon Germanium (eSiGe) is used in the channel region of PFET devices at the 22-nm FD SOI node. The use of eSiGe results in channel regions becoming strained, which results in better hole mobility and increased performance. However, if the active diffusion regions are too short on each side of a PFET gate, then the effect of channel strain is reduced, and performance is reduced. The Continuous Active Diffusion (CnRx) layout construct suggested by the foundry is a way to help keep channel strain present within a single-cell design. In this article, the CnRx construct is implemented in a 22-nm FD SOI test chip and soft error rates (SER) of stacked-transistor flip-flops (FFs) are shown to increase with heavy ion irradiation. The effect of channel strain on PFETs results in higher collected charges from ion strikes, and charges are more easily passed between adjacent transistors through strained channels. However, with careful schematic and layout design, these effects can be mitigated to produce both high-performance and radiation-tolerant cells using the CnRx construct.

Published
2023
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25. Effect of Substrate Temperature on the Structural, Optical and Electrical Properties of DC Magnetron Sputtered VO 2 Thin Films.

Author

Zhang, Chunzi, Gunes, Ozan, Wen, Shi-Jie, Yang, Qiaoqin, and Kasap, Safa

Subjects
THIN films, MAGNETRON sputtering, DC sputtering, PHASE transitions, ZINC oxide films, TEMPERATURE effect
Abstract

This study focuses on the effect of the substrate temperature (TS) on the quality of VO2 thin films prepared by DC magnetron sputtering. TS was varied from 350 to 600 °C and the effects on the surface morphology, microstructure, optical and electrical properties of the films were investigated. The results show that TS below 500 °C favors the growth of V2O5 phase, whereas higher TS (≥500 °C) facilitates the formation of the VO2 phase. Optical characterization of the as-prepared VO2 films displayed a reduced optical transmittance ( T ˜ ) across the near-infrared region (NIR), reduced phase transition temperature (Tt), and broadened hysteresis width (ΔH) through the phase transition region. In addition, a decline of the luminous modulation (Δ T ˜ lum) and solar modulation ( Δ T ˜ sol ) efficiencies of the as-prepared films have been determined. Furthermore, compared with the high-quality films reported previously, the electrical conductivity (σ) as a function of temperature (T) reveals reduced conductivity contrast (Δσ) between the insulating and metallic phases of the VO2 films, which was of the order of 2. These outcomes indicated the presence of defects and unrelaxed lattice strain in the films. Further, the comparison of present results with those in the literature from similar works show that the preparation of high-quality films at TS lower than 650 °C presents significant challenges. [ABSTRACT FROM AUTHOR]

Published
2022
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29. Design for soft error resiliency in internet core routers

Author

Silburt, Allan L., Evans, Adrian, Perryman, Ian, Wen, Shi-Jie, and Alexandrescu, Dan

Subjects
Bridge/routers -- Design and construction, Integrated circuits -- Design and construction, Semiconductor chips -- Design and construction, Bridge/router, Internetworking device, ISDN router, Product reliability, Standard IC, Company business management, Business, Electronics, Electronics and electrical industries
Published
2009

31. Specification and verification of soft error performance in reliable internet core routers

Author

Silburt, Allan L., Evans, Adrian, Burghelea, Ana, Wen, Shi-Jie, Ward, David, Norrish, Ron, and Hogle, Dean

Subjects
Computer networks -- Analysis, Information networks -- Analysis, Bridge/routers -- Analysis, Bridge/router, Internetworking device, ISDN router, Business, Electronics, Electronics and electrical industries
Abstract

This paper presents a methodology for developing a specification for soft error performance of an integrated hardware/ software system that must achieve highly reliable operation. The methodology enables tradeoffs between reliability and cost to be made during the early silicon design and SW architecture phase. An accelerated measurement technique using neutron beam irradiation is also described that ties the final system performance to the reliability model and specification. The methodology is illustrated for the design of a line card for an internet core router. Index Terms--Communication system reliability, computer network reliability, integrated circuit design, integrated circuit radiation effects, neutron beams, neutron radiation effects, single event upset (SEU).

Published
2008

33. Synthesis, structure and optical properties of high-quality VO2 thin films grown on silicon, quartz and sapphire substrates by high temperature magnetron sputtering: Properties through the transition temperature

Author

Zhang, Chunzi, primary, Koughia, Cyril, additional, Güneş, Ozan, additional, Luo, Jun, additional, Hossain, Nazmul, additional, Li, Yuanshi, additional, Cui, Xiaoyu, additional, Wen, Shi-Jie, additional, Wong, Rick, additional, Yang, Qiaoqin, additional, and Kasap, Safa, additional

Published
2020
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39. Self-heating-induced electrical and optical switching in high quality VO2 films controlled with current pulses.

Author

Gunes, Ozan, Koughia, Cyril, Zhang, Chunzi, Belev, George, Wen, Shi-Jie, Yang, Qiaoqin, and Kasap, Safa O.

Subjects
OPTICAL switching, PERCOLATION theory, MAGNETRONS, MAGNETRON sputtering, ELECTRIC conductivity, SAPPHIRES
Abstract

Self-heating (SH)-induced electrical and optical switching in high quality VO2 films grown by magnetron sputtering on a c-cut sapphire substrate has been investigated under various applied constant current pulses (ID). The effect of SH on the behavior of electrical conductivity (σ), optical transmittance ( T ~) , and film temperature (T) examined by applying a constant current pulse of various magnitudes with a pulse duration of five seconds (Δt = 5 s) in VO2 films which were pre-heated to and stabilized at 57 °C, at the brink of insulator-to-metal transition (IMT). The SH effect that arose from the application of constant ID pulses led to a significant increase in T and substantial changes in σ and T ~ . Observations showed that, depending on the magnitude of ID, the σ and T ~ demonstrate strikingly different temporal behavior not only during the SH-induced IMT but also after the removal of ID. The observed phenomena could be explained using a simple model based on percolation theory previously proposed for the present system. The outcome of the model is confirmed by the results of the structural IMT obtained by Raman micromapping. [ABSTRACT FROM AUTHOR]

Published
2021
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48. A Digital Ultrasonic Endoscope System for Medical Imaging

Author

温世杰 Wen Shi-jie, 周浩 Zhou Hao, 陈晓冬 Chen Xiaodong, 郁道银 Yu Daoyin, and 李明 Li Ming

Subjects
Quality (physics), Optics, Transducer, Image quality, business.industry, Computer science, Medical imaging, Digital imaging, Ultrasonic sensor, business, Rotation, Signal, Atomic and Molecular Physics, and Optics
Abstract

The development of a novel push-type ultrasonic endoscope is described in which probe rotation is accomplished by a small motor situated near the transducer. A digital FPGA-based ultrasound imaging system is implemented which uses coded excitation to increase the SNR and penetration depth, with probe rotation accomplished by a small motor situated near the transducer replacing the external motor and the long steel wire used in other ultrasonic endoscopes. The apparatus is tested continuously for 300 hours with no obvious problems. The coded excitation, digital quadrature demodulation imaging system can obtain ultrasonic images of higher quality and more information of the echo is preserved compared with the analog imaging system, because the analog digital conversion is moved to the first step of the signal processing.The digital imaging system possesses a higher SNR resulting in a sharp image. Locating the motor near the probe improves the consistency of rotational speed in comparison with external guide-wire rotation, and increases the image quality and life-span of these devices.

Published
2010

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