Journal articles: 'Instabilté de Vth'

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Senzaki, Junji, Atsushi Shimozato, Kazutoshi Kojima, Shinsuke Harada, Keiko Ariyoshi, Takahito Kojima, Yasunori Tanaka, and Hajime Okumura. "Threshold Voltage Instability of SiC-MOSFETs on Various Crystal Faces." Materials Science Forum 778-780 (February 2014): 521–24. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.521.

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Threshold voltage (VTH) of SiC-MOSFETs on various crystal faces has been investigated systematically using the same bias-temperature-stress (BTS) conditions. In addition, dependences of gate-oxide-forming process on VTH instability is also discussed. Nitridation treatments such as N2O and NH3 post-oxidation annealing (POA) are effective in stabilization of VTH under both positive-and negative-BTS tests regardless of crystal face. On the other hand, serious VTH instability was confirmed in MOSFETs with gate oxide by pyrogenic oxidation followed by H2 POA.

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Tadjer, Marko J., Karl D. Hobart, Eugene A. Imhoff, and Fritz J. Kub. "Temperature and Time Dependent Threshold Voltage Instability in 4H-SiC Power DMOSFET Devices." Materials Science Forum 600-603 (September 2008): 1147–50. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.1147.

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Threshold voltage (Vth) was measured on 4H-SiC power DMOSFET devices as a function of temperature, gate stress, and gate stress time. Vth varied linearly with gate stress and gate stress time and inversely with temperature. This instability is explained with the trapping rate of channel electrons at or near the SiO2-SiC interface. Since the measurement scale of Vth is large in this case (it takes approx. 20 s to measure Vth), it is assumed that fast interface traps, i.e., ones closer to the interface, are already filled and do not contribute to the shift in Vth. Comparison with theoretical calculations shows the rate of carrier detrapping becomes higher with temperature and as a result the measured value of Vth approaches the theoretical value.

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Sometani, Mitsuru, Dai Okamoto, Shinsuke Harada, Hitoshi Ishimori, Shinji Takasu, Tetsuo Hatakeyama, Manabu Takei, Yoshiyuki Yonezawa, Kenji Fukuda, and Hajime Okumura. "Exact Characterization of Threshold Voltage Instability in 4H-SiC MOSFETs by Non-Relaxation Method." Materials Science Forum 821-823 (June 2015): 685–88. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.685.

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In this work, we investigated the methods that measure the threshold voltage (Vth) instability without relaxation of the gate stress during the Vth measurement. We propose a non-relaxation method that demonstrates exact Vth shifts compared with conventional methods that are not as accurate. In the non-relaxation method, the constant gate-source voltage (Vgs) is continuously applied as a gate stress while the drain voltage (Vds) shift required to maintain a constant drain current (Id) is measured. Then, the Vds shift is converted to a Vth shift. The Vth shift values measured by the non-relaxation method are larger than those measured by the other methods, which means that the non-relaxation method can very accurately measure the Vth shift.

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Na, Jeong-Hyeon, Jun-Hyeong Park, Won Park, Junhao Feng, Jun-Su Eun, Jinuk Lee, Sin-Hyung Lee, et al. "Dependence of Positive Bias Stress Instability on Threshold Voltage and Its Origin in Solution-Processed Aluminum-Doped Indium Oxide Thin-Film Transistors." Nanomaterials 14, no. 5 (March 4, 2024): 466. http://dx.doi.org/10.3390/nano14050466.

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The initial electrical characteristics and bias stabilities of thin-film transistors (TFTs) are vital factors regarding the practical use of electronic devices. In this study, the dependence of positive bias stress (PBS) instability on an initial threshold voltage (VTH) and its origin were analyzed by understanding the roles of slow and fast traps in solution-processed oxide TFTs. To control the initial VTH of oxide TFTs, the indium oxide (InOx) semiconductor was doped with aluminum (Al), which functioned as a carrier suppressor. The concentration of oxygen vacancies decreased as the Al doping concentration increased, causing a positive VTH shift in the InOx TFTs. The VTH shift (∆VTH) caused by PBS increased exponentially when VTH was increased, and a distinct tendency was observed as the gate bias stress increased due to a high vertical electric field in the oxide dielectric. In addition, the recovery behavior was analyzed to reveal the influence of fast and slow traps on ∆VTH by PBS. Results revealed that the effect of the slow trap increased as the VTH moved in the positive direction; this occured because the main electron trap location moved away from the interface as the Fermi level approached the conduction band minimum. Understanding the correlation between VTH and PBS instability can contribute to optimizing the fabrication of oxide TFT-based circuits for electronic applications.

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Kutsuki, Katsuhiro, Sachiko Kawaji, Yukihiko Watanabe, Masatoshi Tsujimura, Toru Onishi, Hirokazu Fujiwara, Kensaku Yamamoto, and Takashi Kanemura. "Impact of Al Doping Concentration at Channel Region on Mobility and Threshold Voltage Instability in 4H-SiC Trench N-MOSFETs." Materials Science Forum 858 (May 2016): 607–10. http://dx.doi.org/10.4028/www.scientific.net/msf.858.607.

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The effect of Al doping concentration (NA) at channel regions ranging from 1.0×1017 to 4.0×1017 cm-3 on the effective channel mobility of electron (μeff) and the threshold voltage (Vth) instability under the positive bias-temperature-stress conditions has been investigated througu the use of trench-gate 4H-SiC MOSFETs with m-face (1-100) channel regions. It was found that μeff degraded with an increase in NA. On the other hand, the increase of NA enlarged the Vth instability. These results indicate that NA has a large impact not only on the Vth value but also on the channel resistance and reliability in 4H-SiC trench MOSFETs.

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Senzaki, Junji, Atsushi Shimozato, Kozutoshi Kajima, Keiko Aryoshi, Takahito Kojima, Shinsuke Harada, Yasunori Tanaka, Hiroaki Himi, and Hajime Okumura. "Electrical Properties of MOS Structures on 4H-SiC (11-20) Face." Materials Science Forum 740-742 (January 2013): 621–24. http://dx.doi.org/10.4028/www.scientific.net/msf.740-742.621.

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Threshold voltage (VTH) instability, channel mobility and oxide reliability have been investigated for meta-oxide-semiconductor (MOS) structures on 4H-SiC (11-20) face using various gate oxidation procedures. Channel mobility of n-channel MOSFET with a gate oxide by pyrogenic oxidation is higher than that by dilute-DRY oxidation followed by a nitrous oxide (N2O) post-oxidation annealing (POA). On the other hand, oxide reliability for the pyrogenic oxides is poor compared with the dilute-DRY/N2O oxides. A Hydrogen POA is effective in an improvement of channel mobility for both oxides, but causes a harmful effect on VTH stability. Temperature dependence of VTH instability indicates that MOS structure grown by dilute-DRY followed by N2O POA is suitable for a practical use of SiC MOS power devices.

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Kim, Sang Sub, Pyung Ho Choi, Do Hyun Baek, Jae Hyeong Lee, and Byoung Deog Choi. "Abnormal Threshold Voltage Shifts in P-Channel Low-Temperature Polycrystalline Silicon Thin Film Transistors Under Negative Bias Temperature Stress." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 7555–58. http://dx.doi.org/10.1166/jnn.2015.11167.

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In this research, we have investigated the instability of P-channel low-temperature polycrystalline silicon (poly-Si) thin-film transistors (LTPS TFTs) with double-layer SiO2/SiNX dielectrics. A negative gate bias temperature instability (NBTI) stress was applied and a turn-around behavior phenomenon was observed in the Threshold Voltage Shift (Vth). A positive threshold voltage shift occurs in the first stage, resulting from the negative charge trapping at the SiNX/SiO2 dielectric interface being dominant over the positive charge trapping at dielectric/Poly-Si interface. Following a stress time of 7000 s, the Vth switches to the negative voltage direction, which is “turn-around” behavior. In the second stage, the Vth moves from −1.63 V to −2 V, overwhelming the NBTI effect that results in the trapping of positive charges at the dielectric/Poly-Si interface states and generating grain-boundary trap states and oxide traps.

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Okamoto, Mitsuo, Mitsuru Sometani, Shinsuke Harada, Hiroshi Yano, and Hajime Okumura. "Dynamic Characterization of the Threshold Voltage Instability under the Pulsed Gate Bias Stress in 4H-SiC MOSFET." Materials Science Forum 897 (May 2017): 549–52. http://dx.doi.org/10.4028/www.scientific.net/msf.897.549.

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The threshold voltage (Vth) instability of 4H-SiC MOSFETs was investigated using high-speed IV measurement instrument. DC stress measurement of wide time span ranging from 10-6 to 103 s without relaxation effect was conducted. The high-speed measurement allowed of dynamic ΔVth measurement under pulsed AC gate bias stress. We investigated effects of NO POA in gate oxidation process on the Vth instabilities.

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Deb, Arkadeep, Jose Ortiz-Gonzalez, Mohamed Taha, Saeed Jahdi, Phillip Mawby, and Olayiwola Alatise. "Impact of Turn-Off Gate Voltage and Temperature on Threshold Voltage Instability in Pulsed Gate Voltage Stresses of SiC MOSFETs." Materials Science Forum 1091 (June 5, 2023): 61–66. http://dx.doi.org/10.4028/p-lidhbt.

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Bias temperature instability (BTI) in SiC MOSFETs has come under significant academic and industrial research. Threshold voltage (VTH) shift due to gate voltage stress has been demonstrated in several studies investigating gate oxide reliability in SiC MOSFETs. Results have shown positive.VTH shift occurs due to electron trapping (PBTI), and negative VTH shift occurs due to hole trapping (NBTI). In this paper, VTH shift is studied for unipolar and bipolar gate pulses with frequencies ranging from 1Hz to 100 kHz. The turn-OFF voltage for the unipolar VGS pulse is 0 V. In the case of the bipolar VGS pulses, two turn-OFF voltages are investigated, namely VGS-OFF = -3V and VGS-OFF= -5V. VTH shift is measured after 1000 seconds with recovery times in the range of 20 milliseconds, and preconditioning is performed before VTH measurement. These measurements have been performed at 25°C and 150°C on a commercially available SiC Planar MOSFET and a SiC Trench MOSFET. The results show that -3 V is enough for de-trapping sufficient electrons while -5V results in increased NBTI, which is accelerated by higher temperatures.

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Rescher, Gerald, Gregor Pobegen, and Thomas Aichinger. "Impact of Nitric Oxide Post Oxidation Anneal on the Bias Temperature Instability and the On-Resistance of 4H-SiC nMOSFETs." Materials Science Forum 821-823 (June 2015): 709–12. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.709.

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We study the impact of different nitric oxide (NO) post oxidation annealing (POA) procedures on the on resistance Ron of n-channel MOSFETs and on the threshold voltage shift ∆Vth following positive bias temperature stress (PBTS). All samples were annealed in an NO containing atmosphere at various temperatures and times. A positive stress voltage of 30 V was chosen which corresponds to an electric field of about 4.3 MV/cm. The NO POA causes a decrease in overall ∆Vth for longer NO POA times and higher NO POA temperatures. As opposed to the change in ∆Vth, the device Ron increases with NO POA temperature and time.

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Li, Shanjie, Peiye Sun, Zhiheng Xing, Nengtao Wu, Wenliang Wang, and Guoqiang Li. "Degradation mechanisms of Mg-doped GaN/AlN superlattices HEMTs under electrical stress." Applied Physics Letters 121, no. 6 (August 8, 2022): 062101. http://dx.doi.org/10.1063/5.0094957.

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GaN-based high electron mobility transistors (HEMTs) have exhibited great application prospects in power and radio frequency devices, thanks to the superior properties of GaN. Despite the significant commercialization progress, the reliability of GaN-based HEMTs remains a challenge. This work experimentally investigates the time-dependent degradation of Mg-doped GaN/AlN superlattice HEMTs under both OFF-state and SEMI-ON-state bias conditions and proposes that GaN/AlN superlattices as a barrier can solve the Vth instability issues of GaN HEMTs under OFF-state and SEMI-ON-state bias conditions. On the one hand, in the SEMI-ON-state, the hot electron effect leads to the degradation of Ig, gm,max, and Id,sat to varying degrees. However, the as-prepared GaN-based HEMTs exhibit excellent Vth stability (almost no change) under hot electron injection, on the account of the excellent two-dimensional electron gas confinement in the GaN/AlN superlattice structure. On the other hand, in the OFF-state, positive Vth shift (about 0.12 V) is induced by the hole emission in the GaN/AlN superlattice structure under reverse bias stress. In addition, the stress-induced destruction of MgO gate dielectric gives rise to the gate leakage, which increases by 2 orders of magnitude and triggers an irreversible degradation (about 10%) of the gm,max. These results are expected to provide a solution to the Vth instability of GaN HEMTs.

12

Li, Xiangdong, Meng Wang, Jincheng Zhang, Rui Gao, Hongyue Wang, Weitao Yang, Jiahui Yuan, et al. "Revealing the Mechanism of the Bias Temperature Instability Effect of p-GaN Gate HEMTs by Time-Dependent Gate Breakdown Stress and Fast Sweeping Characterization." Micromachines 14, no. 5 (May 12, 2023): 1042. http://dx.doi.org/10.3390/mi14051042.

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The bias temperature instability (BTI) effect of p-GaN gate high-electron-mobility transistors (HEMTs) is a serious problem for reliability. To uncover the essential cause of this effect, in this paper, we precisely monitored the shifting process of the threshold voltage (VTH) of HEMTs under BTI stress by fast sweeping characterizations. The HEMTs without time-dependent gate breakdown (TDGB) stress featured a high VTH shift of 0.62 V. In contrast, the HEMT that underwent 424 s of TDGB stress clearly saw a limited VTH shift of 0.16 V. The mechanism is that the TDGB stress can induce a Schottky barrier lowering effect on the metal/p-GaN junction, thus boosting the hole injection from the gate metal to the p-GaN layer. This hole injection eventually improves the VTH stability by replenishing the holes lost under BTI stress. It is the first time that we experimentally proved that the BTI effect of p-GaN gate HEMTs was directly dominated by the gate Schottky barrier that impeded the hole supply to the p-GaN layer.

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Wu, Ruizhu, Simon Mendy, Nereus Agbo, Jose Ortiz Gonzalez, Saeed Jahdi, and Olayiwola Alatise. "Performance of Parallel Connected SiC MOSFETs under Short Circuits Conditions." Energies 14, no. 20 (October 19, 2021): 6834. http://dx.doi.org/10.3390/en14206834.

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This paper investigates the impact of parameter variation between parallel connected SiC MOSFETs on short circuit (SC) performance. SC tests are performed on parallel connected devices with different switching rates, junction temperatures and threshold voltages (VTH). The results show that VTH variation is the most critical factor affecting reduced robustness of parallel devices under SC. The SC current conducted per device is shown to increase under parallel connection compared to single device measurements. VTH shift from bias–temperature–instability (BTI) is known to occur in SiC MOSFETs, hence this paper combines BTI and SC tests. The results show that a positive VGS stress on the gate before the SC measurement reduces the peak SC current by a magnitude that is proportional to VGS stress time. Repeating the measurements at elevated temperatures reduces the time dependency of the VTH shift, thereby indicating thermal acceleration of negative charge trapping. VTH recovery is also observed using SC measurements. Similar measurements are performed on Si IGBTs with no observable impact of VGS stress on SC measurements. In conclusion, a test methodology for investigating the impact of BTI on SC characteristics is presented along with key results showing the electrothermal dynamics of parallel devices under SC conditions.

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Koo, Sang-Mo, and Tae-Jun Ha. "Improved Photo-Induced Stability in Amorphous Metal-Oxide Based TFTs for Transparent Displays." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 7800–7803. http://dx.doi.org/10.1166/jnn.2015.11193.

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In this paper, we investigate the origin of photo-induced instability in amorphous metal-oxide based thin-film transistors (oxide-TFTs) by exploring threshold voltage (Vth) shift in transfer characteristics. The combination of photo irradiation and prolonged gate bias stress enhanced the shift in Vth in amorphous hafnium-indium-zinc-oxide (a-HfIZO) TFTs. Such results stem from the extended trapped charges at the localized defect states related to oxygen vacancy which play a role in a screening effect on the electric field induced by gate voltage. We also demonstrate the chemically clean interface in oxide-TFTs by employing oxygen annealing which reduces the density of trap states, thereby resulting in improved photo-induced stability. We believe that this work stimulates the research society of transparent electronics by providing a promising approach to suppress photo-induced instability in metal-oxide TFTs.

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Asllani, Besar, Alberto Castellazzi, Dominique Planson, and Hervé Morel. "Subthreshold Drain Current Hysteresis of Planar SiC MOSFETs." Materials Science Forum 963 (July 2019): 184–88. http://dx.doi.org/10.4028/www.scientific.net/msf.963.184.

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V TH instabilities of SiC MOSFET are made of a permanent and a recoverable part. VTH hysteresis is a recoverable instability which affects the operation of the device since the threshold voltage depends on the negative bias applied previously. In this paper, the phenomenon is assessed through experiments and TCAD simulation. The results are in good agreement and show that the VTH hysteresis is mainly caused by the hole trapping in the oxide near the interface. The C(V) characteristics of the measured device is similar to the simulated device having a concentration of 1012 holes/cm2 trapped at the interface.

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Grossl Bade, Tamiris, Hassan Hamad, Adrien Lambert, Hervé Morel, and Dominique Planson. "Threshold Voltage Measurement Protocol “Triple Sense” Applied to GaN HEMTs." Electronics 12, no. 11 (June 3, 2023): 2529. http://dx.doi.org/10.3390/electronics12112529.

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The threshold voltage instability in p-GaN gate high electron mobility transistors (HEMTs) has been brought into evidence in recent years. It can lead to reliability issues in switching applications, and it can be followed by other degradation mechanisms. In this paper, a Vth measurement protocol established for SiC MOSFETs is applied to GaN HEMTs: the triple sense protocol, which uses voltage bias to precondition the transistor gate. It has been experimentally verified that the proposed protocol increased the stability of the Vth measurement, even for measurements following degrading voltage bias stress on both drain and gate.

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Liu, Han-Wen, Tzu-Cheng Hung, and Bo-Xiang Huang. "(Digital Presentation) Instability of α-Si:H TFTs under Simultaneous Ultraviolet Light Illumination and Different Bias Stresses." ECS Meeting Abstracts MA2022-02, no. 35 (October 9, 2022): 1262. http://dx.doi.org/10.1149/ma2022-02351262mtgabs.

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Hydrogenated amorphous silicon thin-film transistors (α-Si:H TFTs ) are widely applied in liquid crystal displays (LCD). They can be used as not only the switching devices in the panel but also the scan driving circuit in the active-matrix liquid crystal displays (AMLCD), as well as large-area optical imaging sensor arrays. The α-Si:H could be deposited on the glass or plastic substrates at the low temperature, good uniformity in the large area, and the process is relatively mature, so it is still a competitive material. This study would investigate the deterioration of the α-Si:H TFTs under various bias stressing conditions with and without UV light. For the DC bias stress on the gate terminal, the electron trapping within the gate dielectric under positive bias would cause the threshold voltage (Vth) to shift to the positive direction, but the hole trapping under negative bias would cause the Vth to shift to the negative one. Furthermore, under the DC bias stress, the UV light illuminates the TFTs simultaneously, and the active layer of TFTs would generate additional electrons and holes, which would increase the trapping probability of charges and the amount of degradation and recovery. Both effects of the electron capture in the dielectric and defects creation in the channel would cause the Vth to shift to the positive direction, so the degradation of TFTs under positive bias stress is relatively serious. The increment of the subthreshold swing of TFTs under negative bias stress would be much larger than those under positive one, and the captured holes are easily released in the reverse sweeping mode, leading to the decrease of the drain current. Therefore, the amount of degradation and recovery of the TFTs under negative bias stress is relatively small in the reverse sweeping mode, because the energy barrier of holes is smaller than that of electrons in the interface of α-Si:H/SiNx. For the experiments of AC bias stress on the gate terminal with UV light illuminating simultaneously, the frequency of AC signal is fixed at 10 KHz. It could be found that the leakage current in the cut-off region under negative bias (-35 ~ 0 V) stress would increase with the stress time lasting, which shows that the holes are trapped within the gate dielectric closer to the active layer at the high frequency. These shallow positive trapped charges would attract the electrons to accumulate in the channel region, which causes the drain current to increase gradually. However, under bipolar bias (-17.5 ~ +17.5 V) stress, the charge trapping would first dominate the Vth degradation of TFTs, and then the defect states creation would gradually dominate the change of the Vth as the stress time increasing, which causes the Vth first to shift to the negative direction and then to positive one. For another experiments of AC bias stress on the gate terminal without UV light illumination, the frequencies of AC signals are fixed at 10 Hz and 10 KHz with different ranges of biasing voltages. It could be found that the Vth degradation of TFTs at different frequencies under the higher positive bias cycle (0 ~ +35 and -10 ~ +25 V) is not obviously different, mainly because the speed of electron’s accumulation and disappearance in the channel region could keep up with the switching speed of AC signals. However, it could be found that during the higher negative bias cycle(-35 ~ 0 and -25 ~ +10 V), the amount of change in the Vth at low frequency is relatively larger than that at high frequency, which is due to the RC delay effect of the n+α-Si:H layer on the holes under negative bias stress. To investigate the recovery behavior of TFTs, including the direction and amount of the Vth change in the resting time, we could know the dominating mechanism that leads to the TFT’s degradation. And the probably balanced AC bias stress condition is about -10 ~ +25 V. As the magnitude of negative biasing voltage increases, the holes capture within the gate dielectric would increase, and the drain current in the cut-off region also increases. Finally, the β parameter, in the formula of ΔVth= Atβ, is obtained by fitting the trends of ΔVth v.s. stress times. The value of β parameter would exhibits the influence of different mechanisms on the degradation of TFTs stressed by different bias conditions and with/without UV light illumination over the stressing time. And these results are consistent with above experimental data.

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Rescher, Gerald, Gregor Pobegen, and Tibor Grasser. "Threshold Voltage Instabilities of Present SiC-Power MOSFETs under Positive Bias Temperature Stress." Materials Science Forum 858 (May 2016): 481–84. http://dx.doi.org/10.4028/www.scientific.net/msf.858.481.

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We study the threshold voltage (Vth) instability of commercially available silicon carbide (SiC) power MOSFETs or prototypes from four different manufacturers under positive bias temperature stress (PBTS). A positive bias near the Vth causes a threshold voltage shift of 0.7 mV per decade in time per nanometer oxide thickness in the temperature range between-50 °C and 150 °C. Recovery at +5 V after a 100 s +25 V gate-pulse causes a recovery between-1.5 mV/dec/nm and-1.0 mV/dec/nm at room temperature and is decreasing with temperature. All devices show similar stress, recovery and temperature dependent behavior indicating that the observed Vth instabilities are likely a fundamental physical property of the SiC-SiO2 system caused by electron trapping in near interface traps. It is important to note that the trapping is not causing permanent damage to the interface like H-bond-breakage in silicon based devices and is nearly fully reversible via a negative gate bias.

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Go, Donghyun, Gilsang Yoon, Jounghun Park, Donghwi Kim, Jiwon Kim, Jungsik Kim, and Jeong-Soo Lee. "Effect of Noncircular Channel on Distribution of Threshold Voltage in 3D NAND Flash Memory." Micromachines 14, no. 11 (October 28, 2023): 2007. http://dx.doi.org/10.3390/mi14112007.

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The instability in threshold voltage (VTH) and charge distributions in noncircular cells of three-dimensional (3D) NAND flash memory are investigated. Using TCAD simulation, we aim to identify the main factors influencing the VTH of noncircular cells. The key focus is on the nonuniform trapped electron density in the charge trapping layer (CTL) caused by the change in electric field between the circular region and the spike region. There are less-trapped electron (LT) regions within the CTL of programmed noncircular cells, which significantly enhances current flow. Remarkably, more than 50% of the total current flows through these LT regions when the spike size reaches 15 nm. We also performed a comprehensive analysis of the relationship between charge distribution and VTH in two-spike cells with different heights (HSpike) and angles between spikes (θ). The results of this study demonstrate the potential to improve the reliability of next-generation 3D NAND flash memory.

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Elangovan, Surya, Stone Cheng, and Edward Yi Chang. "Reliability Characterization of Gallium Nitride MIS-HEMT Based Cascode Devices for Power Electronic Applications." Energies 13, no. 10 (May 21, 2020): 2628. http://dx.doi.org/10.3390/en13102628.

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We present a detailed study of dynamic switching instability and static reliability of a Gallium Nitride (GaN) Metal-Insulator-Semiconductor High-Electron-Mobility-Transistor (MIS-HEMT) based cascode switch under off-state (negative bias) Gate bias stress (VGS, OFF). We have investigated drain channel current (IDS, Max) collapse/degradation and turn-on and rise-time (tR) delay, on-state resistance (RDS-ON) and maximum transconductance (Gm, max) degradation and threshold voltage (VTH) shift for pulsed and prolonged off-state gate bias stress VGS, OFF. We have found that as stress voltage magnitude and stress duration increases, similarly IDS, Max and RDS-ON degradation, VTH shift and turn-on/rise time (tR) delay, and Gm, max degradation increases. In a pulsed off-state VGS, OFF stress experiment, the device instabilities and degradation with electron trapping effects are studied through two regimes of stress voltages. Under low stress, VTH shift, IDS collapse, RDS-ON degradation has very minimal changes, which is a result of a recoverable surface state trapping effect. For high-stress voltages, there is an increased and permanent VTH shift and high IDS, Max and RDS-ON degradation in pulsed VGS, Stress and increased rise-time and turn-on delay. In addition to this, a positive VTH shift and Gm, max degradation were observed in prolonged stress experiments for selected high-stress voltages, which is consistent with interface state generation. These findings provide a path to understand the failure mechanisms under room temperature and also to accelerate the developments of emerging GaN cascode technologies.

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LEE, YONG K. "CONTROLLING INSTABILITIES OF HYDROGENERATED a-Si:H TFT UNDER BIAS TEMPERATURE STRESSING." Modern Physics Letters B 22, no. 04 (February 10, 2008): 263–68. http://dx.doi.org/10.1142/s0217984908014730.

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The hydrogenerated amorphous silicon a-Si:H thin film transistors TFT with silicon nitride as a gate insulator have been stressed with independently varying gate (Vg), source (Vs), and gate-source (Vgs) bias voltage in order to elucidate the instability mechanism and suggest the new a-Si:H TFT structure. It was found that there was dependency of threshold voltage shift not only on Vgs, but also on Vg and Vs, which had not ever been reported. Its shift amount increased with increasing Vs and/or Vg. In this reports, we suggested the new TFT device structure to eliminate the dependency of Vth shift on Vg and Vs and found that with the new suggested TFT structure, the Vth shift controlling factor can only be Vgs.

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Lee, Sangmin, Pyungho Choi, Minjun Song, Gaeun Lee, Nara Lee, Bohyeon Jeon, and Byoungdeog Choi. "Negative Bias Instability of InZnO-Based Thin-Film Transistors Under Illumination Stress." Journal of Nanoscience and Nanotechnology 21, no. 8 (August 1, 2021): 4277–84. http://dx.doi.org/10.1166/jnn.2021.19392.

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In this study, we investigated the threshold voltage (Vth) instability of solution-processed indium zinc oxide (IZO) thin film transistors (TFTs) prior to and after negative bias illumination stress (NBIS) with varying carrier suppressors (Ga, Al, Hf, and Zr). Variations in electrical properties of the IZO-based TFTs as a function of carrier suppressors were attributed to the differences in metal-oxygen bonding energy of the materials, which was numerically verified by calculating the relative oxygen deficient ratio from the X-ray photoelectron spectroscopy analysis. Furthermore, the values of Vth shift (ΔVth) of the devices subjected to negative gate bias stress under 635 nm (red), 530 nm (green), and 480 nm (blue) wavelength light irradiation increased as the incident photon energy increased. IZO TFTs doped with Ga atoms demonstrated weaker metal-oxygen bonding energy compared to the others and exhibited the largest ΔVth. This result was attributed to the suppressor-dependent distribution of neutral oxygen vacancies which determine the degrees of photon energy absorption in the IZO films. Then, the ΔVth instability of IZO-based TFTs under NBIS correlated well with a stretched exponential function.

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Lee, Seung-Hun, Kihwan Kwon, Kwanoh Kim, Jae Sung Yoon, Doo-Sun Choi, Yeongeun Yoo, Chunjoong Kim, Shinill Kang, and Jeong Hwan Kim. "Electrical, Structural, Optical, and Adhesive Characteristics of Aluminum-Doped Tin Oxide Thin Films for Transparent Flexible Thin-Film Transistor Applications." Materials 12, no. 1 (January 3, 2019): 137. http://dx.doi.org/10.3390/ma12010137.

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The properties of Al-doped SnOx films deposited via reactive co-sputtering were examined in terms of their potential applications for the fabrication of transparent and flexible electronic devices. Al 2.2-atom %-doped SnOx thin-film transistors (TFTs) exhibit improved semiconductor characteristics compared to non-doped films, with a lower sub-threshold swing of ~0.68 Vdec−1, increased on/off current ratio of ~8 × 107, threshold voltage (Vth) near 0 V, and markedly reduced (by 81%) Vth instability in air, attributable to the decrease in oxygen vacancy defects induced by the strong oxidizing potential of Al. Al-doped SnOx films maintain amorphous crystallinity, an optical transmittance of ~97%, and an adhesive strength (to a plastic substrate) of over 0.7 kgf/mm; such films are thus promising semiconductor candidates for fabrication of transparent flexible TFTs.

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Lim, Sang Chul, Seong Hyun Kim, Gi Heon Kim, Jae Bon Koo, Jung Hun Lee, Chan Hoe Ku, Yong Suk Yang, Do Jin Kim, and Tae Hyoung Zyung. "Instability of OTFT with Organic Gate Dielectrics." Solid State Phenomena 124-126 (June 2007): 407–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.407.

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We report the effects of instability with gate dielectrics of pentacene thin film transistors (OTFTs) inverter circuits. We used to the UV sensitive curable resin and poly-4-vinylphenol(PVP) by gate dielectrics. The inverter supply bias is VDD= -40 V. For a given dielectric thickness and applied voltage, pentacene OTFTs with inverter circuits measurements field effect mobility, on-off current ratio, Vth. The field effect mobility 0.03~0.07 cm2/Vs, and the threshold voltage is -3.3 V ~ -8.8 V. The on- and off-state currents ratio is about 103~106. From the OTFT device and inverter circuit measurement, we observed hysteresis behavior was caused by interface states of between the gate insulator and the pentacene semiconductor layer.

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Dreger, Christian, and Jürgen Wolters. "Instabile Geldnachfrage im Euroraum?" Vierteljahrshefte zur Wirtschaftsforschung 76, no. 4 (October 2007): 85–95. http://dx.doi.org/10.3790/vjh.76.4.85.

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Elangovan, Surya, Edward Yi Chang, and Stone Cheng. "Analysis of Instability Behavior and Mechanism of E-Mode GaN Power HEMT with p-GaN Gate under Off-State Gate Bias Stress." Energies 14, no. 8 (April 13, 2021): 2170. http://dx.doi.org/10.3390/en14082170.

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In this study, we investigate the degradation characteristics of E-mode GaN High Electron Mobility Transistors (HEMTs) with a p-GaN gate by designed pulsed and prolonged negative gate (VGS) bias stress. Device transfer and transconductance, output, and gate-leakage characteristics were studied in detail, before and after each pulsed and prolonged negative VGS bias stress. We found that the gradual degradation of electrical parameters, such as threshold voltage (VTH) shift, on-state resistance (RDS-ON) increase, transconductance max (Gm, max) decrease, and gate leakage current (IGS-Leakage) increase, is caused by negative VGS bias stress time evolution and magnitude of stress voltage. The significance of electron trapping effects was revealed from the VTH shift or instability and other parameter degradation under different stress voltages. The degradation mechanism behind the DC characteristics could be assigned to the formation of hole deficiency at p-GaN region and trapping process at the p-GaN/AlGaN hetero-interface, which induces a change in the electric potential distribution at the gate region. The design and application of E-mode GaN with p-GaN gate power devices still need such a reliability investigation for significant credibility.

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Gonzalez, Jose Ortiz, Olayiwola Alatise, and Philip A. Mawby. "Novel Method for Evaluation of Negative Bias Temperature Instability of SiC MOSFETs." Materials Science Forum 963 (July 2019): 749–52. http://dx.doi.org/10.4028/www.scientific.net/msf.963.749.

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The material properties of SiC make SiC power devices a superior alternative to the conventional Si power devices. However, the reliability of the gate oxide has been a major concern, limiting the adoption of SiC power MOSFETs as the power semiconductor of choice in applications which demand a high reliability. The threshold voltage (VTH) shift caused by Bias Temperature Instability (BTI) has focused the attention of different researchers, with multiple publications on this topic. This paper presents a novel method for evaluating the threshold voltage shift due to negative gate bias and its recovery when the gate bias stress is removed. This method could enable gate oxide reliability assessment techniques and contribute to new qualification methods.

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Murakami, Eiichi, Takahiro Furuichi, Tatsuya Takeshita, and Kazuhiro Oda. "Suppression of PBTI of SiC-MOSFETs under 100 kHz Gate-Switching Operation by Using a Gate Off-Voltage of -5 V." Materials Science Forum 924 (June 2018): 711–14. http://dx.doi.org/10.4028/www.scientific.net/msf.924.711.

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Positive bias temperature instability (PBTI) is one of the crucial issues in SiC-MOSFETs’ introduction to automotive applications. We have investigated PBTI of commercially available SiC-MOSFETs under gate-switching operation to consider real power circuits operation. The use of negative gate off-voltage (Vgs(OFF)~-5 V) is shown to suppress Vth shift (ΔVth) under 100 kHz gate-switching operation. This gate voltage corresponds to the flat band condition, under which the electrons trapped by the near-interfacial traps are effectively detrapped through the interface states around the conduction band edge.

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Park, Jee Ho, Sohyung Lee, Hee Sung Lee, Sung Ki Kim, Kwon-Shik Park, and Soo-Young Yoon. "Correlation between spin density and Vth instability of IGZO thin-film transistors." Current Applied Physics 18, no. 11 (November 2018): 1447–50. http://dx.doi.org/10.1016/j.cap.2018.08.016.

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Wang, Kai Yu, Cai Ping Wan, Wen Hao Lu, Nian Nian Ge, and Heng Yu Xu. "Factors Affecting Bias Temperature Instability in 4H-SiC MOS Capacitors." Key Engineering Materials 950 (July 31, 2023): 133–38. http://dx.doi.org/10.4028/p-fagd0d.

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The threshold voltage of 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) show instability during normal operation, especially after bias temperature stress (BTS), and this phenomenon is called bias temperature instability (BTI). In this work, to study the factors affecting threshold voltage (Vth) instability of SiC MOSFETs, flat-band voltage (Vfb) instability of 4H-SiC metal-oxide-semiconductor (MOS) capacitors is discussed instead. Some factors, including the polarity of gate bias stress, stress time, and stress temperature, are analyzed by performing one-way bias stress C-V measurements in the devices. Firstly, positive bias stress leads to a positive Vfb shift, and negative bias stress leads to a negative one. Moreover, the Vfb shift appears to exhibit a linear relationship with log (stress time). Furthermore, the Vfb shift decreases over the temperature range of 225 K to 400 K, but slightly increases at 475 K. Finally, the Vfb stability of the MOS devices fabricated by 1200 °C NO post-oxidation annealing (POA) and those fabricated by 1250 °C NO POA is similar.

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Idris, Muhammad I., Ming Hung Weng, H. K. Chan, A. E. Murphy, Dave A. Smith, R. A. R. Young, Ewan P. Ramsay, David T. Clark, Nick G. Wright, and Alton B. Horsfall. "Electrical Stability Impact of Gate Oxide in Channel Implanted SiC NMOS and PMOS Transistors." Materials Science Forum 897 (May 2017): 513–16. http://dx.doi.org/10.4028/www.scientific.net/msf.897.513.

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Operation of SiC MOSFETs beyond 300°C opens up opportunities for a wide range of CMOS based digital and analogue applications. However the majority of the literature focuses only on the optimization of a single type of MOS device (either PMOS or more commonly NMOS) and there is a lack of a comprehensive study describing the challenge of optimizing CMOS devices. This study reports on the impact of gate oxide performance in channel implanted SiC on the electrical stability for both NMOS and PMOS capacitors and transistors. Parameters including interface state density (Dit), flatband voltage (VFB), threshold voltage (VTH) and effective charge (NEFF) have been acquired from C-V characteristics to assess the effectiveness of the fabrication process in realising high quality gate dielectrics. The performance of SiC based CMOS transistors were analyzed by correlating the characteristics of the MOS interface properties, the MOSFET 1/f noise performance and transistor on-state stability at 300°C. The observed instability of PMOS devices is more significant than in equivalent NMOS devices. The results from MOS capacitors comprising interface state density (Dit), flatband voltage (VFB), threshold voltage (VTH) for both N and P MOS are in agreement with the expected characteristics of the respective transistors.

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Dreger, Christian, and Jürgen Wolters. "Hat die Finanzkrise zu einer instabilen Geldnachfrage geführt?" Vierteljahrshefte zur Wirtschaftsforschung 79, no. 4 (October 2010): 135–45. http://dx.doi.org/10.3790/vjh.79.4.135.

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Li, Jiye, Yuqing Zhang, Hao Peng, Huan Yang, Lei Lu, and Shengdong Zhang. "9.2: Mechanism of H₂O‐induced Instability of Self‐Aligned Top‐Gate Amorphous InGaZnO TFTs." SID Symposium Digest of Technical Papers 54, S1 (April 2023): 94–97. http://dx.doi.org/10.1002/sdtp.16230.

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The influence of H2O on self‐aligned top‐gate (SATG) a‐ InGaZnO thin‐film transistor (TFT) was systematically investigated by performing the high‐temperature high‐humidity (HTHH) test (50 °C, 80% RH). Though initial electrical characteristics were well maintained, the stability under positive bias stress (PBS) was considerably deteriorated, including an abnormal negative Vth shift, degraded SS, and increased off current. The mechanism of H2O‐induced instability was proposed to be the dissociation of H2O molecules and the migration of hydrogen (H) atoms into the a‐IGZO channel. The hydrogen diffusion and doping effects in SATG a‐IGZO TFTs were further proved by SiNx‐passivated TFTs with regulated H content in SiNx layers.

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Ruderman, M. S., E. Verwichte, R. Erdélyi, and M. Goossens. "Dissipative instability of the MHD tangential discontinuity in magnetized plasmas with anisotropic viscosity and thermal conductivity." Journal of Plasma Physics 56, no. 2 (October 1996): 285–306. http://dx.doi.org/10.1017/s0022377800019279.

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The stability of the MHD tangential discontinuity is studied in compressible plasmas in the presence of anisotropic viscosity and thermal conductivity. The general dispersion equation is derived, and solutions to this dispersion equation and stability criteria are obtained for the limiting cases of incompressible and cold plasmas. In these two limiting cases the effect of thermal conductivity vanishes, and the solutions are only influenced by viscosity. The stability criteria for viscous plasmas are compared with those for ideal plasmas, where stability is determined by the Kelvin—Helmholtz velocity VKH as a threshold for the difference in the equilibrium velocities. Viscosity turns out to have a destabilizing influence when the viscosity coefficient takes different values at the two sides of the discontinuity. Viscosity lowers the threshold velocity V below the ideal Kelvin—Helmholtz velocity VKH, so that there is a range of velocities between V and VKH where the overstability is of a dissipative nature.

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Huang, Sen, Shu Yang, John Roberts, and Kevin J. Chen. "Characterization of Vth-instability in Al2O3/GaN/AlGaN/GaN MIS-HEMTs by quasi-static C-V measurement." physica status solidi (c) 9, no. 3-4 (February 29, 2012): 923–26. http://dx.doi.org/10.1002/pssc.201100302.

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Cho, Sanghyun, Seohan Kim, Doyeong Kim, Moonsuk Yi, Junseok Byun, and Pungkeun Song. "Effects of Yttrium Doping on a-IGZO Thin Films for Use as a Channel Layer in Thin-Film Transistors." Coatings 9, no. 1 (January 15, 2019): 44. http://dx.doi.org/10.3390/coatings9010044.

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Amorphous In−Ga−Zn−O (a-IGZO) has been studied as a channel layer in thin-film transistors (TFTs). To improve the bias-induced instability of a-IGZO TFTs, we introduced yttrium with high bond enthalpy by magnetron co-sputtering system. The Y-doped a-IGZO (a-IGZO:Y) films show relatively lower carrier concentration and higher Hall mobility, which is due to the suppression of oxygen vacancies caused by Y doping. The a-IGZO:Y showed a relatively higher transmittance in the visible light region compared to non-doped IGZO, which could be due to the decrease of shallow defect levels caused by oxygen vacancy in the band gap. The a-IGZO without Y doping showed dramatic changes in electrical properties as times progressed (over 240 h); however, the a-IGZO:Y showed no significant changes. The a-IGZO:Y TFTs demonstrated a more stable driving mode as exhibited in the positive gate bias stress test even though the values of VTH and SS were slightly degraded.

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Florentin, Matthieu, Mihaela Alexandru, Aurore Constant, Bernd Schmidt, and Philippe Godignon. "10 MeV Proton Irradiation Effect on 4H-SiC nMOSFET Electrical Parameters." Materials Science Forum 806 (October 2014): 121–25. http://dx.doi.org/10.4028/www.scientific.net/msf.806.121.

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This work presents the 10 MeV protons irradiation effects on 4H-SiC MOSFETs at different fluences. MOSFETs main electrical parameters, such as the channel mobility (µEFF), threshold voltage (VTH), transconductance (gm) and subthreshold current, were analyzed using the time bias stress instability (BSI) technique. Applying this method allowed us to study the effect of carriers interaction with generated interface traps, whether in the bulk or at the interface. Improvements, such as VTHstabilization in time and a significant increase of the µEFFat high fluencies, have been noticed. We assume that this behavior is connected with the atomic diffusion from the SiO2/SiC interface, towards the epilayer during proton irradiation. These atoms, in majority Nitrogen, may create other bonds by occupying various vacancies coming from Silicon and Carbon’s dangling bond. Therefore, by enhancing the passivated Carbon atoms number, we show that high irradiation proton could be a way to improve the SiO2/SiC interface quality.

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Bai, Zhi Qiang, Xiao Yan Tang, Chao Han, Yan Jing He, Qing Wen Song, Yi Fan Jia, Yi Men Zhang, and Yu Ming Zhang. "The Influence of Temperature Storage on Threshold Voltage Stability for SiC VDMOSFET." Materials Science Forum 954 (May 2019): 144–50. http://dx.doi.org/10.4028/www.scientific.net/msf.954.144.

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Even with SiC power MOSFETs released into the commercial market, the threshold voltage instability caused by near interface states is still an attracting issue, which is a major obstacle to further improving the device performance. In this paper, the effects of temperature storage on the threshold voltage stability of n-channel 4H-SiC VDMOSFET are studied. It is found that the capture of hole traps is dominant during the long-term temperature storage at 425 K, causing a considerable negative shift of threshold voltage. In view of the influence of temperature storage, the positive and negative drift trends of threshold voltage slow down during the gate-bias stress measurement. And the ∆VTH, the difference between the threshold voltages recorded after positive and negative gate-bias stress in the same duration, also grows slowly with the increasing stress duration. Finally, some suggestions for improving the threshold reliability of n-channel SiC VDMOSFETs are presented.

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Slobounov, Semyon, Cheng Cao, Niharika Jaiswal, and Karl M. Newell. "Neural basis of postural instability identified by VTC and EEG." Experimental Brain Research 199, no. 1 (August 5, 2009): 1–16. http://dx.doi.org/10.1007/s00221-009-1956-5.

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Franck Severin Ando, Amalaman. "Milieu Institutionnel, Sexe Et Stabilité Émotionnelle/Névrosisme Chez Des Orphelins Et Enfants Vulnérables Du Fait Du VIH À Abidjan." European Scientific Journal, ESJ 18, no. 14 (April 30, 2022): 116. http://dx.doi.org/10.19044/esj.2022.v18n14p116.

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Le présent travail évalue l’influence séparée et conjointe de la vie en milieu institutionnel et du sexe sur la stabilité émotionnelle ou le névrosisme chez des orphelins et enfants rendus vulnérables du fait du VIH (OEV). Quatre-vingt-trois (83) sujets âgés de 12-17 ans suivis au Centre Intégré de Recherches Biocliniques d’Abidjan (CIRBA) ont pris part à l’enquête. Ceux-ci ont été soumis à un questionnaire sociodémographique ainsi qu’à l’inventaire de personnalité de H. Eysenck (1971). Les résultats indiquent d’une part, que les adolescents vivant en milieu institutionnel tendent à développer le névrosisme comparativement à leurs homologues vivant avec au moins un membre de la famille. En fait, les premiers se sentent abandonnés par leur famille et leur vie quotidienne est rythmée de rituels liés à la prise en charge du VIH/Sida, notamment les prises du traitement ARV. D’autre part, que les garçons font plus preuve de stabilité émotionnelle par rapport aux filles, car celles-ci se projettent très souvent dans leur vie d’adulte, en considérant la difficulté à avoir un conjoint qui accepte leur sérologie VIH positive. Par ailleurs, les filles vivant en milieu institutionnel connaissent une instabilité émotionnelle par rapport aux garçons qui vivent avec au moins un membre de famille. The present study evaluates the separate and joint influence of institutional life and gender on emotional stability or neuroticism in orphans and children made vulnerable by HIV (OVC). Eighty-three (83) subjects aged 12-17 years followed at the Centre Intégré de Recherches Biocliniques d'Abidjan (CIRBA) took part in the survey. They were subjected to a socio-demographic questionnaire as well as to the personality inventory of H. Eysenck (1971). The results indicate that adolescents living in an institutional setting tend to develop neuroticism compared to their counterparts living with at least one family member. In fact, the former feel abandoned by their family and their daily life is punctuated by rituals related to the management of HIV/AIDS, particularly the taking of ARV treatment. On the other hand, boys are more emotionally stable than girls, because they often project themselves into their adult lives, considering the difficulty of having a spouse who accepts their positive HIV status. On the other hand, girls living in institutional settings experience emotional instability compared to boys who live with at least one family member.

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Neema, Vaibhav, Kuldeep Raguwanshi, Ambika Prasad Shah, and Santosh Kumar Vishvakarma. "Vth Extraction Based Run Time Transistor Width (TWOS) Module for On-Chip Negative Bias Temperature Instability (NBTI) Mitigation." Sensor Letters 17, no. 5 (May 1, 2019): 385–92. http://dx.doi.org/10.1166/sl.2019.4103.

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Wang, Dapeng, Mamoru Furuta, Shigekazu Tomai, and Koki Yano. "Impact of Photo-Excitation on Leakage Current and Negative Bias Instability in InSnZnO Thickness-Varied Thin-Film Transistors." Nanomaterials 10, no. 9 (September 9, 2020): 1782. http://dx.doi.org/10.3390/nano10091782.

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InSnZnO thin-film transistors (ITZO TFTs), having high carrier mobility, guarantee the benefits of potential applications in the next generation of super-high-definition flat-panel displays. However, the impact of photo-excitation on the leakage current and negative bias stress (NBIS) of ITZO TFTs must be further explored. In this study, the ITZO thickness (TITZO) is designed to tailor the initial performance of devices, especially for the 100 nm TITZO TFT, producing excellent electrical properties of 44.26 cm2V−1s−1 mobility, 92 mV/dec. subthreshold swing (SS), 0.04 V hysteresis, and 3.93 × 1010 ON/OFF ratio, which are superior to those of the reported ITZO TFTs. In addition, incident light coupled with tunable photon energy is introduced to monitor the leakage current of various TITZO devices. The OFF-current results demonstrate that under the identical photon energy, many more electrons are photo-excited for the thicker TITZO TFTs. NBIS-induced Vth shift and SS deterioration in all TFTs are traced and analyzed in real time. As the TITZO thickens to near Debye length, the degree of degradation is exacerbated. When the thickness further increases, the notorious instability caused by NBIS is effectively suppressed. This study provides an important research basis for the application of ITZO-based TFTs in future displays.

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Ali, Amjad, Ahmad Naveed, Tahir Rasheed, Tariq Aziz, Muhammad Imran, Ze-Kun Zhang, Muhammad Wajid Ullah, et al. "Methods for Predicting Ethylene/Cyclic Olefin Copolymerization Rates Promoted by Single-Site Metallocene: Kinetics Is the Key." Polymers 14, no. 3 (January 24, 2022): 459. http://dx.doi.org/10.3390/polym14030459.

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In toluene at 50 °C, the vinyl addition polymerization of 4-vinyl-cyclohexene (VCH) comonomers with ethylene is investigated using symmetrical metallocene (rac-Et(Ind)2ZrCl2) combined with borate/TIBA. To demonstrate the polymerizations’ living character, cyclic VCH with linear-exocyclicπ and endocyclicπ bonds produces monomodal polymers, but the dispersity (Ɖ) was broader. The copolymers obtained can be dissolved in conventional organic solvent and have excellent thermal stability and crystalline temperature (ΔHm), and their melting temperature (Tm) varies from 109 to 126 °C, and ΔHm ranges from 80 to 128 (J/g). Secondly, the distribution of polymeric catalysts engaged in polymer chain synthesis and the nature of the dormant state are two of the most essential yet fundamentally unknown aspects. Comprehensive and exhaustive kinetics of E/VCH have shown numerous different kinetic aspects that are interpreted as manifestations of polymeric catalysts or of the instability of several types of active center [Zr]/[C*] fluctuations and formation rates of chain propagation RpE, RpVCH, and propagation rate constants kpE and kpVCH, the quantitative relationship between RpE, RpVCH and kpE, kpVCH and catalyst structures, their constituent polymer Mw, and their reactivity response to the endocyclic and exocyclic bonds of VCH. The kinetic parameters RpE, RpVCH, kpE, and kpVCH, which are the apparent rates for the metallocene-catalyzed E/VCH, RpE, and kpE values, are much more significant than RpVCH and kpVCH at 120 s, RpE and RpVCH 39.63 and 0.78, and the kpE and kpVCH values are 6461 and 93 L/mol·s, respectively, and minor diffusion barriers are recommended in the early stages. Compared with previously reported PE, RpE and kpE values are 34.2 and 7080 L/mol·s. VCH increases the RpE in the initial stage, as we are expecting; this means that the exocyclic bond of VCH is more active at the initial level, and that the chain transfer reaction of cyclic internal π double is increased with the reaction time. The tp versus Rp, kp, and [Zr]/[C*] fraction count may be fitted to a model that invokes deactivation of growing polymer chains. At tp 120–360 s higher, the incorporation rate of VCH suppresses E insertion, resulting in reduced molecular weight.

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Nandi, Abhijit, Manisha, Vandana Solanki, Vishvanath Tiwari, Basavaraj Sajjanar, Muthu Sankar, Mohini Saini, Sameer Shrivastava, S. K. Bhure, and Srikant Ghosh. "Protective Efficacy of Multiple Epitope-Based Vaccine against Hyalomma anatolicum, Vector of Theileria annulata and Crimean–Congo Hemorrhagic Fever Virus." Vaccines 11, no. 4 (April 21, 2023): 881. http://dx.doi.org/10.3390/vaccines11040881.

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Hyalomma anatolicum is the principal vector for Theileria annulata, T. equi, and T. Lestoquardi in animals and the Crimean–Congo hemorrhagic fever virus in humans. Due to the gradual loss of efficacy of the available acaricides against field tick populations, the development of phytoacaricides and vaccines has been considered the two most critical components of the integrated tick management strategies. In the present study, in order to induce both cellular and humoral immune responses in the host against H. anatolicum, two multi-epitopic peptides (MEPs), i.e., VT1 and VT2, were designed. The immune-stimulating potential of the constructs was determined by in silicoinvestigation on allergenicity (non-allergen, antigenic (0.46 and 1.0046)), physicochemical properties (instability index 27.18 and 35.46), as well as the interaction of constructs with TLRs by docking and molecular dynamics analysis. The immunization efficacy of the MEPs mixed with 8% MontanideTM gel 01 PR against H. anatolicum larvae was determined as 93.3% and 96.9% in VT1- and VT2-immunized rabbits, respectively. Against adults, the efficacy was 89.9% and 86.4% in VT1- and VT2-immunized rabbits, respectively. A significant (p < 0.001) reduction in the anti-inflammatory cytokine (IL-4) and significantly higher IgG response was observed in a VT1-immunized group of rabbits as compared with the response observed in the control group. However, in the case of the VT2-immunized rabbits, an elevated anti-VT2 IgG and pro-inflammatory cytokine (IL-2) (>30 fold) along with a decreased level of anti-inflammatory cytokine IL-4 (0.75 times) was noted. The efficacy of MEP and its potential immune stimulatory responses indicate that it might be useful for tick management.

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Aktershev, Yuriy, Sergey Vasichev, and Vladimir Veremeenko. "Precision Four-Quadrant Current Source Vch-500-12r For Superconducting Solenoids." Siberian Journal of Physics 12, no. 2 (June 1, 2017): 138–41. http://dx.doi.org/10.54362/1818-7919-2017-12-2-138-141.

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A precision controllable bidirectional current source 0-500A for superconducting solenoids used in particle physics experiments has been proposed. This article discusses the operation principle of the designed device including a 40-kHz voltage conversion with subsequent synchronous rectification and an approach to energy recuperation from large inductive loads. It also presents some circuit designs aimed at reducing switching losses and increasing the overall efficiency. Current instability for 8 hours of continuous operation is no more than 0.01 % of the normal current.

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Jung, Seyeon, Taehoon Sung, Sein Lee, and J. Y. Kwon. "Control of Hydrogen Concentration in Ingazno Thin Film Using Cryopumping System." ECS Meeting Abstracts MA2022-01, no. 31 (July 7, 2022): 1333. http://dx.doi.org/10.1149/ma2022-01311333mtgabs.

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Recently, amorphous metal-oxide semiconductors (AOSs) such as indium gallium zinc oxide (IGZO) have attracted great attention with their lower power consumption and higher mobility than amorphous silicon in the display field. However, the threshold voltage (Vth) shift of IGZO thin film transistor (TFT) caused by their poor reliability leads to the drop panel luminance. Therefore, improvement of IGZO TFT reliability is necessary, which is largely influenced by oxygen vacancy and hydrogen. In particular, hydrogen has shown different roles inside the IGZO active layer by hydrogen concentration. At lower concentration, the hydrogen passivation of oxygen deficiency region induces the improvement of initial electrical characteristics and reliability [2]. Meanwhile, Vth shift and degradation reliability are generated at higher concentration owing to the hydrogen related defect states [3]. Therefore, controlling excess hydrogen is necessary for reliability enhancement. In this work, IGZO thin film was fabricated by cryopumping system instead of a turbo molecular pump (TMP) for radio frequency sputtering to reduce hydrogen concentration. Cryopump is an adsorption type that enables excellent evacuation ability of hydrogen and moisture taking up most of the partial pressure in high vacuum. As a result, deposition of IGZO thin film with lower hydrogen impurity is available. The hydrogen concentration in the IGZO thin film using both cryopump and TMP was quantitatively analyzed by elastic recoil detection (ERD) analysis. Then, electrical characteristics of the self-aligned top-gate structure TFTs fabricated by both pumps were measured with bias stress conditions. To sum up, we showed the improved reliability of IGZO TFT by controlling excess hydrogen using cryopumping system. Fig.1. (a) Schematic of RF magnetron sputtering process with cryopump. (b) TOF-SIMS depth profiles of hydrogen concentration in IGZO film using TMP and cryopump Acknowledgment This work was supported by the Korea Evaluation Institute of Industrial Technology(KEIT) grant funded by the Korea government (MOTIE) (No. 2021-11-1283) References Chung, Ui-Jin, et al. "15‐1: Invited Paper: Manufacturing Technology of LTPO TFT." SID Symposium Digest of Technical Papers. Vol. 51. No. 1. 2020. Hanyu, Yuichiro, et al. "Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors." Applied Physics Letters 103.20 (2013): 202114. Mativenga, Mallory, et al. "Origin of light instability in amorphous IGZO thin-film transistors and its suppression." Scientific reports 11.1 (2021): 1-12 Figure 1

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Ortel, Thomas L., Karen D. Moore, Mirella Ezban, and William H. Kane. "Effect of Heterologous Factor V Heavy Chain Sequences on the Secretion of Recombinant Human Factor VIII." Thrombosis and Haemostasis 75, no. 01 (1996): 036–44. http://dx.doi.org/10.1055/s-0038-1650218.

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SummaryFactor VIII and factor V share a repetitive domain structure of A1-A2-B-A3-C1-C2. To define the region(s) within the factor VIII heavy chain that result in inefficient expression of the recombinant protein, we expressed a series of factor VIH/factor V chimeras that contained heterologous sequences from the A1 and/or A2 domains. Substitution of the factor VIIIA1 domain dramatically reduced secretion of factor V ~ 500-fold, whereas substitution of the factor VIII A2 domain had minimal effect on secretion. Conversely, substitution of the factor V A1 domain increased secretion of factor VIII ~3-fold, whereas substitution of the factor V A2 domain actually reduced secretion ~4-fold. Pulse chase experiments confirmed that reduced expression levels were due to decreased secretion rather than instability of secreted protein. Smaller substitutions did not further localize within the A1 domain the regions responsible for inefficient secretion.

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Besnier, Niko. "Les politiques identitaires entre le local et le global : la mobilisation transgenre aux îles Tonga (Pacifique sud)." Ethnologie française Vol. 54, no. 1 (February 26, 2024): 117–33. http://dx.doi.org/10.3917/ethn.241.0117.

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Au cours des dernières décennies, des ONG internationales ont développé dans les pays dits du « Sud » des politiques d’émancipation fondées sur une lecture universalisante des pratiques et des identités de genre et de sexualité qui ne se conforment pas aux normes conventionnelles. Mais certains critiques soutiennent que, loin d’avoir un effet libératoire, ces politiques induisent de nouvelles formes de répression. Aux îles Tonga, tous les projets sociaux ou personnels s’effectuent dans le cadre d’une « vision à double foyer » (local et global) associée à une instabilité profonde du contexte local. Les transgenres (de sexe biologique masculin) sont particulièrement sensibles à ces dynamiques et contestent les moralités locales en suggérant que leurs pratiques doivent être évaluées à l’aune d’un contexte cosmopolite associé en particulier aux discours globaux de prévention du VIH. Mais des discours répressifs jusqu’alors peu développés ont été aussi introduits dans le cadre de moralités associées au pentecôtisme et au mormonisme, se voulant tout aussi cosmopolites et à prétention émancipatrices. La circulation globale du discours sur ces questions est donc constituée d’un ensemble complexe de positions et d’idées ne renvoyant pas à une simple distinction entre le local et le global.

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Lee, Geon Hee, Jang Kwon Lim, Sang Mo Koo, and Mietek Bakowski. "Measurement and Analysis of Body Diode Stress of 3.3 kV Sic-Mosfets with Intrinsic Body Diode and Embedded SBD." Materials Science Forum 1091 (June 5, 2023): 55–59. http://dx.doi.org/10.4028/p-nnor4r.

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SiC MOSFETs display reliability issues related to the quality of SiO2/SiC interface and bulk material due to the presence of near interface traps and point and extended material defects [1]. These material related issues give rise to a degradation of device reliability and ruggedness. One of them are basal plane dislocations (BPDs) introduced in the drift-layer during the epitaxial growth process which causes a s.c. bipolar degradation. Growth and movement of BPDs fueled by recombination energy has a very significant impact on conduction loss and on-resistance degradation. For 3.3 kV voltage capability, the probability of the appearance of BPDs is greater because the drift region is about three times larger compared to 1.2 kV devices [2-3]. We present measurement results and analysis of bipolar degradation in 3.3 kV MOSFETs with conventional body diode and embedded schottky barrier diode (SBD). The measurements were performed applying 50 % and 80 % of rated current with duty cycle 80 %, under total time of 100 hrs at constant case temperature of 54 °C. The 3rd-quadrant performance of both types of MOSFETs in pre-stress conditions was characterized at 25 and 150 °C with different gate biases of -10 V, 0 V, and +17 V. To evaluate the bipolar degradation, the diode conduction characteristics were measured at 25 °C after different stressing times by diode conduction the MOSFET output characteristics were measured at 25 and 54 °C before and after stressing the intrinsic body diode and embedded SBD. No VSD shift was observed in diode conduction characteristics. The results indicate that the MOSFETs were fabricated on appropriate material with a sufficiently low number basal plane dislocation (BPD). The on-state resistance with VGS = +17 V was decreased by temperature due to increased JFET resistance rather than bipolar degradation. On the other hand, the on-state resistance with VGS = +11 V was impacted by the increased temperature and VTH instability.

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Singh, N. "Space-time evolution of electron-beam driven electron holes and their effects on the plasma." Nonlinear Processes in Geophysics 10, no. 1/2 (April 30, 2003): 53–63. http://dx.doi.org/10.5194/npg-10-53-2003.

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Abstract. We report here further results from the three-dimensional particle-in-cell simulations of the electron-beam driven electron holes. We focus here on (i) the transformation of oscillatory waves driven by the electron-beam instability into electron holes, (ii) the continued evolution and propagation of electron holes after their formation, including merging of electron holes, and (iii) the effects of the evolution on the plasma density and ion velocity distribution function. We find that initially electron-beam modes with perpendicular wave numbers k^ = 0 and as well as k^ ≠ 0 are driven resonantly below the electron plasma frequency of the target plasma. The modes interact nonlinearly and modulate each other both in space and time, producing wave structures with finite perpendicular scale lengths. Nonlinear evolution of such wave structures generates the electron holes in the simulations. Initially, a large number of electron holes form in the plasma. Their merging yields continuously a decreasing number of electron holes. The propagation velocity of the electron holes evolves dynamically and is affected by their merging. At late times only a few electron holes are left in the simulation and they decay by emitting low-frequency electrostatic whistler waves just above the lower hybrid (LH) frequency vlh . These waves, which are long structures parallel to the ambient magnetic field B0 and quite short transverse to B0, are associated with similar structures in the plasma density, producing density filaments. It turns out that electron-beam driven plasmas, in general, develop such filaments at some stage of the evolution of the beam-driven waves. In view of the excitation of the LH waves near vlh, which could resonate with the ions, an analysis shows that it is possible to heat transversely the ions in a time scale of a few seconds in the auroral return current plasma, in which electron holes and transversely heated ions have been simultaneously observed.

Journal articles on the topic 'Instabilté de Vth'

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