Considering the contribution of both the outer and inner horizons, the Hamilton-Jacobi method is applied to a Kerr-Newman black hole and a negative temperature of the inner horizon is obtained. Under the negative temp...Considering the contribution of both the outer and inner horizons, the Hamilton-Jacobi method is applied to a Kerr-Newman black hole and a negative temperature of the inner horizon is obtained. Under the negative temperature inside the black hole, the thermodynamics of the two horizons is studied, and the new Bekenstein-Smarr formula is given. The entropies of the inner and outer horizons are all positive. The new entropy expression of the black hole satisfies the Nernst Theorem and can be regarded as the Planck absolute entropy.展开更多
The change of the temperature coefficient of resistivity (a) with the particle size, dp, and the grain size, dc, in the nanostructured Ag bulk samples was investigated. dp and dc were controlled by heating the nano-Ag...The change of the temperature coefficient of resistivity (a) with the particle size, dp, and the grain size, dc, in the nanostructured Ag bulk samples was investigated. dp and dc were controlled by heating the nano-Ag powders over the temperature range from 393 to 453 K. The electrical resistance measurements of the nanostructured Ag bulk samples obtained by compacting the Ag powders after heat treatments showed a change in the sign of a with dP and dc. When dp and dc are smaller or equal to 18 and 11 nm below room temperature or 20 and 12 nm above room temperature, respectively, the sign of the temperature coefficient of resistivity changes from positive to negative. The negative a arises mainly from the high resistivity induced by the particle interfaces with very lowly ordered or even disordered structure, a large volume fraction of interfaces and impurities existing in the interfaces, and the quantum size effect appearing in the nano-Ag grains.展开更多
The application of the Unruh procedure to the Rindler approximation of the Kerr-Newman metric in the neighborhood of the event and Cauchy horizons leads, unambiguously, to the well-known positive Hawking (black hole) ...The application of the Unruh procedure to the Rindler approximation of the Kerr-Newman metric in the neighborhood of the event and Cauchy horizons leads, unambiguously, to the well-known positive Hawking (black hole) temperature at the outer horizon, but to a negative (white hole) temperature at the inner horizon. Some consequences for the heat capacities and the status of the third law of thermodynamics are also discussed.展开更多
Negative temperature coefficient(NTC)thermistor plays a crucial role in science research and engineering applications for precise temperature monitoring.Although great progress has been achieved in NTC materials,enhan...Negative temperature coefficient(NTC)thermistor plays a crucial role in science research and engineering applications for precise temperature monitoring.Although great progress has been achieved in NTC materials,enhancing sensitivity and maintaining this high sensitivity along with linearity across extensive temperature ranges remain a significant challenge.In this study,we introduce a diamondbased thermistor(DT)characterized by its outstanding sensitivity,swift response time,and broad temperature monitoring capabilities.The temperature constant B for this DT,measured from 30 to 300°C(B30/300),achieves an exceptional value of 8012 K,which notably exceeds the temperature sensing capabilities of previously reported NTC thermistors within this extensive range.Moreover,diamond’s unique thermal conductivity and stability significantly boost the response speed and durability of the DT,offering substantial advantages over traditional ceramic thermistors.The enhanced temperature-sensitive properties of the DT are attributed to the presence of impurity elements in polycrystalline diamond.Impedance analysis indicates a hopping conduction mechanism,likely involving C-H or C-N dipoles at the diamond grain boundaries.This study marks a significant leap forward in diamond thermistor technology and sheds light on the mechanisms of thermal active conduction in diamond materials.展开更多
The electrical properties of high-entropy ceramics(HECs)have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy engineering...The electrical properties of high-entropy ceramics(HECs)have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy engineering.Novel high-entropy(Sm_(0.2)Eu_(0.2)Gd_(0.2)Ho_(0.2)Yb_(0.2))CrO_(3)(HE-RECrO_(3))nanofibers were prepared by electro spinning.This work demonstrates that HE-RECrO_(3)nanofibe rs were successfully synthesized at a low temperature(800℃),which is approximately 400℃lower than the temperatures at which chromate ceramics were synthesized via the sol-gel method and the solid-state reaction method.The resistivity of HE-RECrO_(3)nanofibers decreases exponentially with increasing temperature from 25 to600℃.The logarithm of the resistivity is linearly related to the inverse of the temperature,confirming the negative temperature coefficient property of HE-RECrO_(3)nanofibers.The B_(25/50)value of the HERECrO_(3)nanofibers reaches 4072 K.In conclusion,HE-RECrO_(3)nanofibers are expected to be potential candidates for negative-temperature-coefficient(NTC)thermistors.展开更多
Dense nano-grained Ni_(0.7)Mn_(2.3O4) negative temperature coefficient(NTC) thermistors were fabricated by a novel two-step sintering approach that combines rapid sintering and principle of conventional two-step sinte...Dense nano-grained Ni_(0.7)Mn_(2.3O4) negative temperature coefficient(NTC) thermistors were fabricated by a novel two-step sintering approach that combines rapid sintering and principle of conventional two-step sintering technique.Samples were sintered at 1042℃ for 30 s in the first rapid step and then at 850-950℃ for 20 h in the second soaking step.Crystal phase,microstructure and electrical properties of sintered samples were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),resistance temperature relationship and aging performance.Sintered samples show a single-phase cubic spinel structure and indicate a high relative density ranging from 84% to 91% of the theoretical density.Moreover,average grain sizes of sintered samples under SEM are distributed between 254 and 570 nm.Meanwhile,the resistivity and the aging coefficient significantly decrease when soaking sintering temperature rises.In addition,the obtained material constant(B) ranges from 3931 to 3981 K.Ni_(0.7)Mn_(2.3)O_(4)-3(soaking at 900℃) and Ni_(0.7)Mn_(2.3O4)-4(soaking at 950℃) present little aging behavior,implying great electrical stability.展开更多
The NBTI degradation phenomenon and the role of hydrogen during NBT stress are presented in this paper. It is found that PBT stress can recover a fraction of Vth shift induced by NBT1. However, this recovery is unstab...The NBTI degradation phenomenon and the role of hydrogen during NBT stress are presented in this paper. It is found that PBT stress can recover a fraction of Vth shift induced by NBT1. However, this recovery is unstable. The original degradation reappears soon after reapplication of the NBT stress condition. Hydrogen-related species play a key role during a device＇s NBT degradation. Experimental results show that the diffusion species are neutral, they repassivate Si dangling bond which is independent of the gate voltage polaxity. In addition to the diffusion towards gate oxide, hydrogen diffusion to Si-substrate must be taken into account for it also has important influence on device degradation during NBT stress.展开更多
This paper studies the effect of drain bias on ultra-short p-channel metal-oxide-semiconductor field-effect transistor （PMOSFET） degradation during negative bias temperature （NBT） stress. When a relatively large g...This paper studies the effect of drain bias on ultra-short p-channel metal-oxide-semiconductor field-effect transistor （PMOSFET） degradation during negative bias temperature （NBT） stress. When a relatively large gate voltage is applied, the degradation magnitude is much more than the drain voltage which is the same as the gate voltage supplied, and the time exponent gets larger than that of the NBT instability （NBTI）. With decreasing drain voltage, the degradation magnitude and the time exponent all get smaller. At some values of the drain voltage, the degradation magnitude is even smaller than that of NBTI, and when the drain voltage gets small enough, the exhibition of degradation becomes very similar to the NBTI degradation. When a relatively large drain voltage is applied, with decreasing gate voltage, the degradation magnitude gets smaller. However, the time exponent becomes larger. With the help of electric field simulation, this paper concludes that the degradation magnitude is determined by the vertical electric field of the oxide, the amount of hot holes generated by the strong channel lateral electric field at the gate/drain overlap region, and the time exponent is mainly controlled by localized damage caused by the lateral electric field of the oxide in the gate/drain overlap region where hot carriers are produced.展开更多
The effect of the static negative bias temperature （NBT） stress on a p-channel power metal-oxide-semiconductor field-effect transistor （MOSFET） is investigated by experiment and simulation. The time evolution of t...The effect of the static negative bias temperature （NBT） stress on a p-channel power metal-oxide-semiconductor field-effect transistor （MOSFET） is investigated by experiment and simulation. The time evolution of the negative bias temperature instability （NBTI） degradation has the trend predicted by the reaction-diffusion （R-D） model but with an exaggerated time scale. The phenomena of the flat-roof section are observed under various stress conditions, which can be considered as the dynamic equilibrium phase in the R-D process. Based on the simulated results, the variation of the flat-roof section with the stress condition can be explained.展开更多
The effect of substrate bias on the degradation during applying a negative bias temperature （NBT） stress is studied in this paper. With a smaller gate voltage stress applied, the degradation of negative bias tempera...The effect of substrate bias on the degradation during applying a negative bias temperature （NBT） stress is studied in this paper. With a smaller gate voltage stress applied, the degradation of negative bias temperature instability （NBTI） is enhanced, and there comes forth an inflexion point. The degradation pace turns larger when the substrate bias is higher than the inflexion point. The substrate hot holes can be injected into oxide and generate additional oxide traps, inducing an inflexion phenomenon. When a constant substrate bias stress is applied, as the gate voltage stress increases, an inflexion comes into being also. The higher gate voltage causes the electrons to tunnel into the substrate from the poly, thereby generating the electro,hole pairs by impact ionization. The holes generated by impact ionization and the holes from the substrate all can be accelerated to high energies by the substrate bias. More additional oxide traps can be produced, and correspondingly, the degradation is strengthened by the substrate bias. The results of the alternate stress experiment show that the interface traps generated by the hot holes cannot be annealed, which is different from those generated by common holes.展开更多
This paper studies negative bias temperature instability （NBTI） under alternant and alternating current （AC） stress. Under alternant stress, the degradation smaller than that of single negative stress is obtained....This paper studies negative bias temperature instability （NBTI） under alternant and alternating current （AC） stress. Under alternant stress, the degradation smaller than that of single negative stress is obtained. The smaller degradation is resulted from the recovery of positive stress. There are two reasons for the recovery. One is the passivation of H dangling bonds, and another is the detrapping of charges trapped in the oxide. Under different frequencies of AC stress, the parameters all show regular degradation, and also smaller than that of the direct current stress. The higher the frequency is, the smaller the degradation becomes. As the negative stress time is too small under higher frequency, the deeper defects are hard to be filled in. Therefore, the detrapping of oxide charges is easy to occur under positive bias and the degradation is smaller with higher frequency.展开更多
A new on-line methodology is used to characterize the negative bias temperature instability （NBTI） without inherent recovery. Saturation drain voltage shift and mobility shift are extracted by ID-VD characterization...A new on-line methodology is used to characterize the negative bias temperature instability （NBTI） without inherent recovery. Saturation drain voltage shift and mobility shift are extracted by ID-VD characterizations, which were measured before stress, and after every certain stress phase, using the proportional differential operator （PDO） method. The new on-line methodology avoids the mobility linearity assumption as compared with the previous onthe-fly method. It is found that both reaction-diffusion and charge-injection processes are important in NBTI effect under either DC or AC stress. A similar activation energy, 0.15 eV, occurred in both DC and AC NBTI processes. Also degradation rate factor is independent of temperature below 90℃ and sharply increases above it. The frequency dependence of NBTI degradation shows that NBTI degradation is independent of frequencies. The carrier tunnelling and reaction-diffusion mechanisms exist simultaneously in NBTI degradation of sub-micron pMOSFETs, and the carrier tunnelling dominates the earlier NBTI stage and the reaction-diffusion mechanism follows when the generation rate of traps caused by carrier tunnelling reaches its maximum.展开更多
The exponent n of the generation of an interface trap （Nit）, which contributes to the power-law negative bias temperature instability （NBTI） degradation, and the exponent’s time evolution are investigated by simu...The exponent n of the generation of an interface trap （Nit）, which contributes to the power-law negative bias temperature instability （NBTI） degradation, and the exponent’s time evolution are investigated by simulations with varying the stress voltage Vg and temperature T. It is found that the exponent n in the diffusion-limited phase of the degradation process is irrelevant to both Vg and T. The time evolution of the exponent n is affected by the stress conditions, which is reflected in the shift of the onset of the diffusion-limited phase. According to the diffusion profiles, the generation of the atomic hydrogen species, which is equal to the buildup of Nit, is strongly correlated with the stress conditions, whereas the diffusion of the hydrogen species shows Vg-unaffected but T-affected relations through the normalized results.展开更多
Hot carrier injection （HCI） at high temperatures and different values of gate bias Vg has been performed in order to study the actions of negative bias temperature instability （NBTI） and hot carriers. Hot-carrier-...Hot carrier injection （HCI） at high temperatures and different values of gate bias Vg has been performed in order to study the actions of negative bias temperature instability （NBTI） and hot carriers. Hot-carrier-stress-induced damage at Vg = Vd, where Vd is the voltage of the transistor drain, increases as temperature rises, contrary to conventional hot carrier behaviour, which is identified as being related to the NBTI. A comparison between the actions of NBTI and hot carriers at low and high gate voltages shows that the damage behaviours are quite different： the low gate voltage stress results in an increase in transconductance, while the NBTI-dominated high gate voltage and high temperature stress causes a decrease in transconductance. It is concluded that this can be a major source of hot carrier damage at elevated temperatures and high gate voltage stressing of p-channel metal-oxide-semiconductor field-effect transistors （PMOSFETs）. We demonstrate a novel mode of NBTI-enhanced hot carrier degradation in PMOSFETs. A novel method to decouple the actions of NBTI from that of hot carriers is also presented.展开更多
High-density polyethylene/carbon black foaming conductive composites were prepared from acetylene black（ACEY） and super conductive carbon black（HG-1P） as conductive filler, low-density polyethylene（LDPE） as the ...High-density polyethylene/carbon black foaming conductive composites were prepared from acetylene black（ACEY） and super conductive carbon black（HG-1P） as conductive filler, low-density polyethylene（LDPE） as the second component, ethylene-vinyl acetate（EVA） and ethylene propylene rubber（EPR） as the third component, azobisformamide（AC） as foamer, and dicumyl peroxide（DCP） as cross-linker. The structure and resistivity-temperature behavior of high-density polyethylene（HDPE）/CB foaming conductive composites were investigated. Influences of carbon black, LDPE, EVA, EPR, AC, and DCP on the foaming performance and resistivity-temperature behavior of HDPE/CB foaming conductive composites were also studied. The results reveal that HDPE/CB foaming conductive composite exhibits better switching characteristic; ACET-filled HDPE foaming conductive composite displays better positive temperature coefficient（PYC） effect; whereas super conductive carbon black（HG-1P）-filled HDPE foaming conductive composite shows better negative temperature coefficient（NTC） effect.展开更多
We report the investigation on the low-temperature oxidation of cyclohexane in a jet-stirred reactor over 500-742 K. Synchrotron vacuum ultraviolet photoionization mass spectrometry （SVUV-PIMS） was used for identify...We report the investigation on the low-temperature oxidation of cyclohexane in a jet-stirred reactor over 500-742 K. Synchrotron vacuum ultraviolet photoionization mass spectrometry （SVUV-PIMS） was used for identifying and quantifying the oxidation species. Major products, cyclic olefins, and oxygenated products including reactive hydroperoxides and high oxygen compounds were detected. Compared with n-alkanes, a narrow low-temperature window （-80 K） was observed in the low-temperature oxidation of cyclohexane. Besides, a kinetic model for cyclohexane oxidation was developed based on the CNRS model [Combust. Flame 160, 2319 （2013）], which can better capture the experimental results than previous models. Based on the modeling analysis, the 1,5-H shift dominates the crucial isomerization steps of the first and second O2 addition products in the low-temperature chain branching process of cyclohexane. The negative temperature coefficient behavior of cyclohexane oxidation results from the reduced chain branching due to the competition from chain inhibition and propagation reactions, i.e. the reaction between cyclohexyl radical and O2 and the de- composition of cyclohexylperoxy radical, both producing cyclohexene and HO2 radical, as well as the decomposition of cyclohexylhydroperoxy radical producing hex-5-en-l-al and OH radical.展开更多
In the conversion of methane and propane under high temperature and pressure,the ignition delay time(IDT)is a key parameter to consider for designing an inherently safe process.In this study,the IDT characteristics of...In the conversion of methane and propane under high temperature and pressure,the ignition delay time(IDT)is a key parameter to consider for designing an inherently safe process.In this study,the IDT characteristics of methane and propane(700–1000 K,10–20 bar)were studied experimentally and using kinetic modeling tools at stoichiometric fuel-tooxygen ratios.All the experiments were conducted through insentropic compression.The reliable experimental data were obtained by using the adiabatic core hypothesis,which can be used to generate and validate the detailed chemical kinetics model.The IDTs of methane and propane were recorded by a rapid compression machine(RCM)and compared to the predicted values obtained by the NUIGMech 3.0 mechanism.To test the applicability of NUIGMech 3.0 under different reaction conditions,the influence of temperature in the range of 700–1000 K(and the influence of pressure in the range of 10–20 bar)on the IDT was studied.The results showed that NUIGMech 3.0 could reasonably reproduce the experimentally determined IDT under the wide range of conditions studied.The constant volume chemical kinetics model was used to reveal the effect of temperature on the elementary reaction,and the negative temperature coefficient(NTC)behavior of propane was also observed at 20 bar.The experimental data can serve as a reference for the correction and application of kinetic data,as well as provide a theoretical basis for the safe conversion of low-carbon hydrocarbon chemicals.展开更多
Y^3＋-doped （Bi 1/2 Na 1/2） TiO 3-CaTiO 3-BaTiO 3 （BNCBT） positive temperature coefficient of resistivity （PTCR） ceramics sintered in air atmosphere were investigated in this study. （Bi 1/2 Na 1/2） TiO 3 （BNT...Y^3＋-doped （Bi 1/2 Na 1/2） TiO 3-CaTiO 3-BaTiO 3 （BNCBT） positive temperature coefficient of resistivity （PTCR） ceramics sintered in air atmosphere were investigated in this study. （Bi 1/2 Na 1/2） TiO 3 （BNT） component can remarkably increase the onset temperature T c of PTCR ceramics with the expense of the resistivity R 25 increase. CaTiO 3 （9–27 mol%） component can decrease the resistivity, and adjust the effects of BNT phase on the T c point. For the sample containing 3 mol% CaTiO 3 , T c raises from 122 ℃ to 153 ℃ when only 0.6 mol% BNT added, while for the ones with higher CaTiO 3 content （9–27 mol%）, T c is only increased by a rate of 8–9℃/1.0 mol% BNT. The effects of BNT and CaTiO 3 components on R25/Rmin （negative temperature coefficient effect） are also discussed.展开更多
In this work, we study approximations of supercritical or suction vortices in tornadic flows and their contribution to tornadogenesis and tornado maintenance using self-avoiding walks on a cubic lattice. We extend the...In this work, we study approximations of supercritical or suction vortices in tornadic flows and their contribution to tornadogenesis and tornado maintenance using self-avoiding walks on a cubic lattice. We extend the previous work on turbulence by A. Chorin and collaborators to approximate the statistical equilibrium quantities of vortex filaments on a cubic lattice when both an energy and a statistical temperature are involved. Our results confirm that supercritical (smooth, “straight”) vortices have the highest average energy and correspond to negative temperatures in this model. The lowest-energy configurations are folded up and “balled up” to a great extent. The results support A. Chorin’s findings that, in the context of supercritical vortices in a tornadic flow, when such high-energy vortices stretch, they need to fold and transfer energy to the surrounding flow, contributing to tornado maintenance or leading to its genesis. The computations are performed using a Markov Chain Monte Carlo approach with a simple sampling algorithm using local transformations that allow the results to be reliable over a wide range of statistical temperatures, unlike the originally used pivot algorithm that only performs well near infinite temperatures. Efficient ways to compute entropy are discussed and show that a system with supercritical vortices will increase entropy by having these vortices fold and transfer their energy to the surrounding flow.展开更多
Degradation induced by the negative bias temperature instability(NBTI)can be attributed to three mutually uncoupled physical mechanisms,i.e.,the generation of interface traps(ΔV_(IT)),hole trapping in pre-existing ga...Degradation induced by the negative bias temperature instability(NBTI)can be attributed to three mutually uncoupled physical mechanisms,i.e.,the generation of interface traps(ΔV_(IT)),hole trapping in pre-existing gate oxide defects(ΔV_(HT)),and the generation of gate oxide defects(ΔV_(OT)).In this work,the characteristic of NBTI for p-type MOSFET fabricated by using a 28-nm high-k metal gate(HKMG)process is thoroughly studied.The experimental results show that the degradation is enhanced at a larger stress bias and higher temperature.The effects of the three underlying subcomponents are evaluated by using the comprehensive models.It is found that the generation of interface traps dominates the NBTI degradation during long-time NBTI stress.Moreover,the NBTI parameters of the power-law time exponent and temperature activation energy as well as the gate oxide field acceleration are extracted.The dependence of operating lifetime on stress bias and temperature is also discussed.It is observed that NBTI lifetime significantly decreases as the stress increases.Furthermore,the decrease of charges related to interface traps and hole detrapping in pre-existing gate oxide defects are used to explain the recovery mechanism after stress.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos.10773002,10875012the National Basic Research Program of China under Grant No.2003CB716302
文摘Considering the contribution of both the outer and inner horizons, the Hamilton-Jacobi method is applied to a Kerr-Newman black hole and a negative temperature of the inner horizon is obtained. Under the negative temperature inside the black hole, the thermodynamics of the two horizons is studied, and the new Bekenstein-Smarr formula is given. The entropies of the inner and outer horizons are all positive. The new entropy expression of the black hole satisfies the Nernst Theorem and can be regarded as the Planck absolute entropy.
基金the National Natural Science FOundation of China under grant! No.19974041the National Major Fundamental ResearCh Program-Nal
文摘The change of the temperature coefficient of resistivity (a) with the particle size, dp, and the grain size, dc, in the nanostructured Ag bulk samples was investigated. dp and dc were controlled by heating the nano-Ag powders over the temperature range from 393 to 453 K. The electrical resistance measurements of the nanostructured Ag bulk samples obtained by compacting the Ag powders after heat treatments showed a change in the sign of a with dP and dc. When dp and dc are smaller or equal to 18 and 11 nm below room temperature or 20 and 12 nm above room temperature, respectively, the sign of the temperature coefficient of resistivity changes from positive to negative. The negative a arises mainly from the high resistivity induced by the particle interfaces with very lowly ordered or even disordered structure, a large volume fraction of interfaces and impurities existing in the interfaces, and the quantum size effect appearing in the nano-Ag grains.
文摘The application of the Unruh procedure to the Rindler approximation of the Kerr-Newman metric in the neighborhood of the event and Cauchy horizons leads, unambiguously, to the well-known positive Hawking (black hole) temperature at the outer horizon, but to a negative (white hole) temperature at the inner horizon. Some consequences for the heat capacities and the status of the third law of thermodynamics are also discussed.
基金supported by the Fundamental Research Funds for the Central Universities(CUG2106117)Hubei Jewelry Engineering Technology Research Center(CIGTXM03202301)+1 种基金Hubei Provincial Natural Science Foundation(20241350053)GuangDong Basic and Applied Basic Research Foundation(2023A1515110043).
文摘Negative temperature coefficient(NTC)thermistor plays a crucial role in science research and engineering applications for precise temperature monitoring.Although great progress has been achieved in NTC materials,enhancing sensitivity and maintaining this high sensitivity along with linearity across extensive temperature ranges remain a significant challenge.In this study,we introduce a diamondbased thermistor(DT)characterized by its outstanding sensitivity,swift response time,and broad temperature monitoring capabilities.The temperature constant B for this DT,measured from 30 to 300°C(B30/300),achieves an exceptional value of 8012 K,which notably exceeds the temperature sensing capabilities of previously reported NTC thermistors within this extensive range.Moreover,diamond’s unique thermal conductivity and stability significantly boost the response speed and durability of the DT,offering substantial advantages over traditional ceramic thermistors.The enhanced temperature-sensitive properties of the DT are attributed to the presence of impurity elements in polycrystalline diamond.Impedance analysis indicates a hopping conduction mechanism,likely involving C-H or C-N dipoles at the diamond grain boundaries.This study marks a significant leap forward in diamond thermistor technology and sheds light on the mechanisms of thermal active conduction in diamond materials.
基金Project supported by the National Key Research and Development Program of China(2019YFC0605000)the"Transformational Technologies for Clean Energy and Demonstration",Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21000000)+4 种基金the Independent Deployment Project of Ganjiang Innovation Research Institute of Chinese Academy of Sciences(E055A002)the Independent Deployment Project of China Fujian Innovation Laboratory of Optoelectronic Information Technology(2021ZZ109)the Fujian Provincial Natural Fund(2021J05101)the National Natural Science Foundation of China(21771196,62275276)Advanced Energy Science and Technology Guangdong Laboratory(HND20TDGFDC00)。
文摘The electrical properties of high-entropy ceramics(HECs)have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy engineering.Novel high-entropy(Sm_(0.2)Eu_(0.2)Gd_(0.2)Ho_(0.2)Yb_(0.2))CrO_(3)(HE-RECrO_(3))nanofibers were prepared by electro spinning.This work demonstrates that HE-RECrO_(3)nanofibe rs were successfully synthesized at a low temperature(800℃),which is approximately 400℃lower than the temperatures at which chromate ceramics were synthesized via the sol-gel method and the solid-state reaction method.The resistivity of HE-RECrO_(3)nanofibers decreases exponentially with increasing temperature from 25 to600℃.The logarithm of the resistivity is linearly related to the inverse of the temperature,confirming the negative temperature coefficient property of HE-RECrO_(3)nanofibers.The B_(25/50)value of the HERECrO_(3)nanofibers reaches 4072 K.In conclusion,HE-RECrO_(3)nanofibers are expected to be potential candidates for negative-temperature-coefficient(NTC)thermistors.
基金financially supported by the National Natural Science Foundation of China(Nos.51302138 and 21663001)the Western Light Talent Training Program of Chinese Academy of Sciences。
文摘Dense nano-grained Ni_(0.7)Mn_(2.3O4) negative temperature coefficient(NTC) thermistors were fabricated by a novel two-step sintering approach that combines rapid sintering and principle of conventional two-step sintering technique.Samples were sintered at 1042℃ for 30 s in the first rapid step and then at 850-950℃ for 20 h in the second soaking step.Crystal phase,microstructure and electrical properties of sintered samples were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),resistance temperature relationship and aging performance.Sintered samples show a single-phase cubic spinel structure and indicate a high relative density ranging from 84% to 91% of the theoretical density.Moreover,average grain sizes of sintered samples under SEM are distributed between 254 and 570 nm.Meanwhile,the resistivity and the aging coefficient significantly decrease when soaking sintering temperature rises.In addition,the obtained material constant(B) ranges from 3931 to 3981 K.Ni_(0.7)Mn_(2.3)O_(4)-3(soaking at 900℃) and Ni_(0.7)Mn_(2.3O4)-4(soaking at 950℃) present little aging behavior,implying great electrical stability.
基金Project supported by the National Natural Science Foundation of China （Grant No 60206006）, the Hi-Tech Research ＆ Development Program of China （Grant No 2004AA1Z1070） and the Key Project of Chinese Ministry of Education （Grant No 104172）.
文摘The NBTI degradation phenomenon and the role of hydrogen during NBT stress are presented in this paper. It is found that PBT stress can recover a fraction of Vth shift induced by NBT1. However, this recovery is unstable. The original degradation reappears soon after reapplication of the NBT stress condition. Hydrogen-related species play a key role during a device＇s NBT degradation. Experimental results show that the diffusion species are neutral, they repassivate Si dangling bond which is independent of the gate voltage polaxity. In addition to the diffusion towards gate oxide, hydrogen diffusion to Si-substrate must be taken into account for it also has important influence on device degradation during NBT stress.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60736033 and 60376024)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2007BAK25B03)
文摘This paper studies the effect of drain bias on ultra-short p-channel metal-oxide-semiconductor field-effect transistor （PMOSFET） degradation during negative bias temperature （NBT） stress. When a relatively large gate voltage is applied, the degradation magnitude is much more than the drain voltage which is the same as the gate voltage supplied, and the time exponent gets larger than that of the NBT instability （NBTI）. With decreasing drain voltage, the degradation magnitude and the time exponent all get smaller. At some values of the drain voltage, the degradation magnitude is even smaller than that of NBTI, and when the drain voltage gets small enough, the exhibition of degradation becomes very similar to the NBTI degradation. When a relatively large drain voltage is applied, with decreasing gate voltage, the degradation magnitude gets smaller. However, the time exponent becomes larger. With the help of electric field simulation, this paper concludes that the degradation magnitude is determined by the vertical electric field of the oxide, the amount of hot holes generated by the strong channel lateral electric field at the gate/drain overlap region, and the time exponent is mainly controlled by localized damage caused by the lateral electric field of the oxide in the gate/drain overlap region where hot carriers are produced.
基金Project supported by the National Basic Research Program of China(Grant No.2011CBA00606)the National Natural Science Foundation of China(Grant No.61106106)
文摘The effect of the static negative bias temperature （NBT） stress on a p-channel power metal-oxide-semiconductor field-effect transistor （MOSFET） is investigated by experiment and simulation. The time evolution of the negative bias temperature instability （NBTI） degradation has the trend predicted by the reaction-diffusion （R-D） model but with an exaggerated time scale. The phenomena of the flat-roof section are observed under various stress conditions, which can be considered as the dynamic equilibrium phase in the R-D process. Based on the simulated results, the variation of the flat-roof section with the stress condition can be explained.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60376024,60736033 and 60506020)the National High Technology Research and Development Program of China (Grant No 2003AA1Z1630)
文摘The effect of substrate bias on the degradation during applying a negative bias temperature （NBT） stress is studied in this paper. With a smaller gate voltage stress applied, the degradation of negative bias temperature instability （NBTI） is enhanced, and there comes forth an inflexion point. The degradation pace turns larger when the substrate bias is higher than the inflexion point. The substrate hot holes can be injected into oxide and generate additional oxide traps, inducing an inflexion phenomenon. When a constant substrate bias stress is applied, as the gate voltage stress increases, an inflexion comes into being also. The higher gate voltage causes the electrons to tunnel into the substrate from the poly, thereby generating the electro,hole pairs by impact ionization. The holes generated by impact ionization and the holes from the substrate all can be accelerated to high energies by the substrate bias. More additional oxide traps can be produced, and correspondingly, the degradation is strengthened by the substrate bias. The results of the alternate stress experiment show that the interface traps generated by the hot holes cannot be annealed, which is different from those generated by common holes.
基金Project supported by the National Key Science and Technology Special Project,China (Grant No. 2008ZX01002-002)the Fundamental Research Funds for the Central Universities,China (Grant No. JY10000904009)the Major Program and State Key Program of the National Natural Science Foundation of China (Grant Nos. 60890191 and 60736033)
文摘This paper studies negative bias temperature instability （NBTI） under alternant and alternating current （AC） stress. Under alternant stress, the degradation smaller than that of single negative stress is obtained. The smaller degradation is resulted from the recovery of positive stress. There are two reasons for the recovery. One is the passivation of H dangling bonds, and another is the detrapping of charges trapped in the oxide. Under different frequencies of AC stress, the parameters all show regular degradation, and also smaller than that of the direct current stress. The higher the frequency is, the smaller the degradation becomes. As the negative stress time is too small under higher frequency, the deeper defects are hard to be filled in. Therefore, the detrapping of oxide charges is easy to occur under positive bias and the degradation is smaller with higher frequency.
文摘A new on-line methodology is used to characterize the negative bias temperature instability （NBTI） without inherent recovery. Saturation drain voltage shift and mobility shift are extracted by ID-VD characterizations, which were measured before stress, and after every certain stress phase, using the proportional differential operator （PDO） method. The new on-line methodology avoids the mobility linearity assumption as compared with the previous onthe-fly method. It is found that both reaction-diffusion and charge-injection processes are important in NBTI effect under either DC or AC stress. A similar activation energy, 0.15 eV, occurred in both DC and AC NBTI processes. Also degradation rate factor is independent of temperature below 90℃ and sharply increases above it. The frequency dependence of NBTI degradation shows that NBTI degradation is independent of frequencies. The carrier tunnelling and reaction-diffusion mechanisms exist simultaneously in NBTI degradation of sub-micron pMOSFETs, and the carrier tunnelling dominates the earlier NBTI stage and the reaction-diffusion mechanism follows when the generation rate of traps caused by carrier tunnelling reaches its maximum.
基金Project supported by the National Basic Research Program of China(Grant No.2011CBA00606)the National Natural Science Foundation of China(Grant No.61106106)the Fundamental Research Funds for the Central Universities,China(Grant No.K50511250008)
文摘The exponent n of the generation of an interface trap （Nit）, which contributes to the power-law negative bias temperature instability （NBTI） degradation, and the exponent’s time evolution are investigated by simulations with varying the stress voltage Vg and temperature T. It is found that the exponent n in the diffusion-limited phase of the degradation process is irrelevant to both Vg and T. The time evolution of the exponent n is affected by the stress conditions, which is reflected in the shift of the onset of the diffusion-limited phase. According to the diffusion profiles, the generation of the atomic hydrogen species, which is equal to the buildup of Nit, is strongly correlated with the stress conditions, whereas the diffusion of the hydrogen species shows Vg-unaffected but T-affected relations through the normalized results.
基金Project supported by the National Natural Science Foundation of China （Grant No 60206006）. the Program for New Century Excellent Talents of Ministry of Education of China （Grant No 681231366）. the National Defense Pre-Research Foundation of China （Grant No 51408010305DZ0168） and the Key Project of Chinese Ministry of Education （Grant No 104172）.
文摘Hot carrier injection （HCI） at high temperatures and different values of gate bias Vg has been performed in order to study the actions of negative bias temperature instability （NBTI） and hot carriers. Hot-carrier-stress-induced damage at Vg = Vd, where Vd is the voltage of the transistor drain, increases as temperature rises, contrary to conventional hot carrier behaviour, which is identified as being related to the NBTI. A comparison between the actions of NBTI and hot carriers at low and high gate voltages shows that the damage behaviours are quite different： the low gate voltage stress results in an increase in transconductance, while the NBTI-dominated high gate voltage and high temperature stress causes a decrease in transconductance. It is concluded that this can be a major source of hot carrier damage at elevated temperatures and high gate voltage stressing of p-channel metal-oxide-semiconductor field-effect transistors （PMOSFETs）. We demonstrate a novel mode of NBTI-enhanced hot carrier degradation in PMOSFETs. A novel method to decouple the actions of NBTI from that of hot carriers is also presented.
文摘High-density polyethylene/carbon black foaming conductive composites were prepared from acetylene black（ACEY） and super conductive carbon black（HG-1P） as conductive filler, low-density polyethylene（LDPE） as the second component, ethylene-vinyl acetate（EVA） and ethylene propylene rubber（EPR） as the third component, azobisformamide（AC） as foamer, and dicumyl peroxide（DCP） as cross-linker. The structure and resistivity-temperature behavior of high-density polyethylene（HDPE）/CB foaming conductive composites were investigated. Influences of carbon black, LDPE, EVA, EPR, AC, and DCP on the foaming performance and resistivity-temperature behavior of HDPE/CB foaming conductive composites were also studied. The results reveal that HDPE/CB foaming conductive composite exhibits better switching characteristic; ACET-filled HDPE foaming conductive composite displays better positive temperature coefficient（PYC） effect; whereas super conductive carbon black（HG-1P）-filled HDPE foaming conductive composite shows better negative temperature coefficient（NTC） effect.
基金supported by the National Natural Science Foundation of China(No.91641205,No.51622605,No.91541201)the Shanghai Science and Technology Committee(No.17XD1402000)
文摘We report the investigation on the low-temperature oxidation of cyclohexane in a jet-stirred reactor over 500-742 K. Synchrotron vacuum ultraviolet photoionization mass spectrometry （SVUV-PIMS） was used for identifying and quantifying the oxidation species. Major products, cyclic olefins, and oxygenated products including reactive hydroperoxides and high oxygen compounds were detected. Compared with n-alkanes, a narrow low-temperature window （-80 K） was observed in the low-temperature oxidation of cyclohexane. Besides, a kinetic model for cyclohexane oxidation was developed based on the CNRS model [Combust. Flame 160, 2319 （2013）], which can better capture the experimental results than previous models. Based on the modeling analysis, the 1,5-H shift dominates the crucial isomerization steps of the first and second O2 addition products in the low-temperature chain branching process of cyclohexane. The negative temperature coefficient behavior of cyclohexane oxidation results from the reduced chain branching due to the competition from chain inhibition and propagation reactions, i.e. the reaction between cyclohexyl radical and O2 and the de- composition of cyclohexylperoxy radical, both producing cyclohexene and HO2 radical, as well as the decomposition of cyclohexylhydroperoxy radical producing hex-5-en-l-al and OH radical.
基金supported by the National Natural Science Foundation of China [Grant No. 22278452]the SINOPEC Research Institute of Safety Engineering for financially supporting this project。
文摘In the conversion of methane and propane under high temperature and pressure,the ignition delay time(IDT)is a key parameter to consider for designing an inherently safe process.In this study,the IDT characteristics of methane and propane(700–1000 K,10–20 bar)were studied experimentally and using kinetic modeling tools at stoichiometric fuel-tooxygen ratios.All the experiments were conducted through insentropic compression.The reliable experimental data were obtained by using the adiabatic core hypothesis,which can be used to generate and validate the detailed chemical kinetics model.The IDTs of methane and propane were recorded by a rapid compression machine(RCM)and compared to the predicted values obtained by the NUIGMech 3.0 mechanism.To test the applicability of NUIGMech 3.0 under different reaction conditions,the influence of temperature in the range of 700–1000 K(and the influence of pressure in the range of 10–20 bar)on the IDT was studied.The results showed that NUIGMech 3.0 could reasonably reproduce the experimentally determined IDT under the wide range of conditions studied.The constant volume chemical kinetics model was used to reveal the effect of temperature on the elementary reaction,and the negative temperature coefficient(NTC)behavior of propane was also observed at 20 bar.The experimental data can serve as a reference for the correction and application of kinetic data,as well as provide a theoretical basis for the safe conversion of low-carbon hydrocarbon chemicals.
基金Project supported by the SPAT of Shanghai Committee of Chinese People's Political Consultative Conference and Shanghai Education Development Foundation (Grant No.2008012)
文摘Y^3＋-doped （Bi 1/2 Na 1/2） TiO 3-CaTiO 3-BaTiO 3 （BNCBT） positive temperature coefficient of resistivity （PTCR） ceramics sintered in air atmosphere were investigated in this study. （Bi 1/2 Na 1/2） TiO 3 （BNT） component can remarkably increase the onset temperature T c of PTCR ceramics with the expense of the resistivity R 25 increase. CaTiO 3 （9–27 mol%） component can decrease the resistivity, and adjust the effects of BNT phase on the T c point. For the sample containing 3 mol% CaTiO 3 , T c raises from 122 ℃ to 153 ℃ when only 0.6 mol% BNT added, while for the ones with higher CaTiO 3 content （9–27 mol%）, T c is only increased by a rate of 8–9℃/1.0 mol% BNT. The effects of BNT and CaTiO 3 components on R25/Rmin （negative temperature coefficient effect） are also discussed.
文摘In this work, we study approximations of supercritical or suction vortices in tornadic flows and their contribution to tornadogenesis and tornado maintenance using self-avoiding walks on a cubic lattice. We extend the previous work on turbulence by A. Chorin and collaborators to approximate the statistical equilibrium quantities of vortex filaments on a cubic lattice when both an energy and a statistical temperature are involved. Our results confirm that supercritical (smooth, “straight”) vortices have the highest average energy and correspond to negative temperatures in this model. The lowest-energy configurations are folded up and “balled up” to a great extent. The results support A. Chorin’s findings that, in the context of supercritical vortices in a tornadic flow, when such high-energy vortices stretch, they need to fold and transfer energy to the surrounding flow, contributing to tornado maintenance or leading to its genesis. The computations are performed using a Markov Chain Monte Carlo approach with a simple sampling algorithm using local transformations that allow the results to be reliable over a wide range of statistical temperatures, unlike the originally used pivot algorithm that only performs well near infinite temperatures. Efficient ways to compute entropy are discussed and show that a system with supercritical vortices will increase entropy by having these vortices fold and transfer their energy to the surrounding flow.
文摘Degradation induced by the negative bias temperature instability(NBTI)can be attributed to three mutually uncoupled physical mechanisms,i.e.,the generation of interface traps(ΔV_(IT)),hole trapping in pre-existing gate oxide defects(ΔV_(HT)),and the generation of gate oxide defects(ΔV_(OT)).In this work,the characteristic of NBTI for p-type MOSFET fabricated by using a 28-nm high-k metal gate(HKMG)process is thoroughly studied.The experimental results show that the degradation is enhanced at a larger stress bias and higher temperature.The effects of the three underlying subcomponents are evaluated by using the comprehensive models.It is found that the generation of interface traps dominates the NBTI degradation during long-time NBTI stress.Moreover,the NBTI parameters of the power-law time exponent and temperature activation energy as well as the gate oxide field acceleration are extracted.The dependence of operating lifetime on stress bias and temperature is also discussed.It is observed that NBTI lifetime significantly decreases as the stress increases.Furthermore,the decrease of charges related to interface traps and hole detrapping in pre-existing gate oxide defects are used to explain the recovery mechanism after stress.
