We study the influences of the temperature on the energy-band structure for the Holstein molecular-crystal model. We show that the energy-band width and the energy-gap width of a solid are relevant to both the interac...We study the influences of the temperature on the energy-band structure for the Holstein molecular-crystal model. We show that the energy-band width and the energy-gap width of a solid are relevant to both the interaction between an electron and thermal phonons and to thermal expansion. For a one-dimensional Li atom lattice chain, under the chosen parameters,the width of the ls and 2s energy bands narrows as the temperature increases and the energy-gap width between the two bands widens. These results agree qualitatively with those observed experimentally. Studying temperature dependence of the energy-band structure is of great importance for understanding optical and transporting characteristics of a solid.展开更多
The temperature dependence of some performance of 6H SiC unipolar power devices is analyzed theoretically.By employing the temperature dependent ionization coefficient and mobility of a silicon carbide,the analytica...The temperature dependence of some performance of 6H SiC unipolar power devices is analyzed theoretically.By employing the temperature dependent ionization coefficient and mobility of a silicon carbide,the analytical expressions of the temperature dependent performance,such as breakdown characteristics and on resistance of 6H SiC unipolar power devices are derived in a closed form.The analytical results are compared with the experimental results,with good accordance found in the breakdown characteristics.展开更多
The temperature dependences of forward voltage drop（VF） of the fast recovery diodes（FRDs） are remarkably influenced by different lifetime controlled treatments. In this paper the results of an experimental study a...The temperature dependences of forward voltage drop（VF） of the fast recovery diodes（FRDs） are remarkably influenced by different lifetime controlled treatments. In this paper the results of an experimental study are presented, which are the lifetime controls of platinum treatment, electron irradiation treatment, and the combined treatment of the above ones.Based on deep level transient spectroscopy（DLTS） measurements, a new level E6（EC-0.376 e V） is found in the combined lifetime treated（CLT） sample, which is different from the levels of the individual platinum and electron irradiation ones. Comparing the tested VFresults of CLT samples with the others, the level E6 is responsible for the degradation of temperature dependence of the forward voltage drop in the FRD.展开更多
In this work, temperature dependences of small-signal model parameters in the SiGe HBT HICUM model are presented. Electrical elements in the small-signal equivalent circuit are first extracted at each temperature, the...In this work, temperature dependences of small-signal model parameters in the SiGe HBT HICUM model are presented. Electrical elements in the small-signal equivalent circuit are first extracted at each temperature, then the temperature dependences are determined by the series of extracted temperature coefficients, based on the established temperature for- mulas for corresponding model parameters. The proposed method is validated by a 1x 0.2 x 16 μm2 SiGe HBT over a wide temperature range （from 218 K to 473 K）, and good matching is obtained between the extracted and modeled resuits. Therefore, we believe that the proposed extraction flow of model parameter temperature dependence is reliable for characterizing the transistor performance and guiding the circuit design over a wide temperature range.展开更多
The temperature dependence of carrier transport properties of Alx Gal-xN/InyGal-yN/CaN and AlzGal-xN/GaN heterostructures has been investigated. It is shown that the Hall mobility in Alo.25Gao.75N/Ino.03Gao.97N/GaN he...The temperature dependence of carrier transport properties of Alx Gal-xN/InyGal-yN/CaN and AlzGal-xN/GaN heterostructures has been investigated. It is shown that the Hall mobility in Alo.25Gao.75N/Ino.03Gao.97N/GaN heterostructures is higher than that in Alo.25Gao.75N/GaN heterostructures at temperatures above 500 K, even the mobility in the former is much lower than that in the latter at 300 K. More importantly, the electron sheet density in Alo.25Gao.75N/Ino.03Gao.97N/GaN heterostructures decreases slightly, whereas the electron sheet density in Al0.25Gao.75N/CaN heterostructures gradually increases with increasing temperature above 500 K. It is believed that an electron depletion layer is formed due to the negative polarization charges at the Iny Can-yN/GaN heterointerface induced by the compressive strain in the InyCal-yN channel, which effectively suppresses the parallel conductivity originating from the thermal excitation in the underlying GaN layer at high temperatures.展开更多
A comparison of the temperature dependence of the P-hit single event transient （SET） in a two-transistor （2T） inverter with that in a three-transistor （3T） inverter is carried out based on a three-dimensional nu...A comparison of the temperature dependence of the P-hit single event transient （SET） in a two-transistor （2T） inverter with that in a three-transistor （3T） inverter is carried out based on a three-dimensional numerical simulation. Due to the significantly distinct mechanisms of the single event change collection in the 2T and the 3T inverters, the temperature plays different roles in the SET production and propagation. The SET pulse will be significantly broadened in the 2T inverter chain while will be compressed in the 3T inverter chain as temperature increases. The investigation provides a new insight into the SET mitigation under the extreme environment, where both the high temperature and the single event effects should be considered. The 3T inverter layout structure （or similar layout structures） will be a better solution for spaceborne integrated circuit design for extreme environments.展开更多
Using three-dimensional technology computer-aided design （TCAD） simulation, parasitic bipolar amplification in a single event transient （SET） current of a single transistor and its temperature dependence are studi...Using three-dimensional technology computer-aided design （TCAD） simulation, parasitic bipolar amplification in a single event transient （SET） current of a single transistor and its temperature dependence are studied. We quantify the contributions of different current components in a SET current pulse, and it is found that the proportion of parasitic bipolar amplification in total collected charge is about 30% in both ]30-nm and 90-nm technologies. The temperature dependence of parasitic bipolar amplification and the mechanism of the SET pulse are also investigated and quantified. The results show that the proportion of charge induced by parasitic bipolar increases with rising temperature, which illustrates that the parasitic bipolar amplification plays an important role in the charge collection of a single transistor.展开更多
The microRaman scattering of 4H-SiC films, fabricated by low pressure chemical vapor deposition under different growth conditions, is investigated at temperatures ranging from 80 K to 550K. The effects of growth condi...The microRaman scattering of 4H-SiC films, fabricated by low pressure chemical vapor deposition under different growth conditions, is investigated at temperatures ranging from 80 K to 550K. The effects of growth conditions on E2 （TO）, E1 （TO） and A1 （LO） phonon mode frequencies are negligible. The temperature dependences of phonon linewidth and lifetime of E2 （TO） modes are analyzed in terms of an anharmonic damping effect induced by thermal and growth conditions. The results show that the lifetime of E2 （TO） mode increases when the quality of the sample improves. Unlike other phone modes, Raman shift of A1 （longitudinal optical plasma coupling （LOPC）） mode does not decrease monotonously when the temperature increases, but tends to blueshift at low temperatures and to redshift at relatively high temperatures. Theoretical analyses are given for the abnormal phenomena of A1 （LOPC） mode in 4H-SiC.展开更多
Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows depende...Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows dependence on temperature, as well as, level of doping. The conductivity is considered to be due to thermal hopping motion of localized charge carriers,which are believed to be polarons, in the temperature range 303 K to 323 K and for T>343 K,whereas. it is metal-like in the temperature range 323 K to 343 K展开更多
The silicon-rich silica films were prepared by a dual-ion-beam co-sputtering method from a composite Target in an argon atmosphere. The structure of the films studied by the aid of TEM and XRD is amorphous. The photol...The silicon-rich silica films were prepared by a dual-ion-beam co-sputtering method from a composite Target in an argon atmosphere. The structure of the films studied by the aid of TEM and XRD is amorphous. The photoluminescence (PL) spectra were found to have a 4- luminescent band peak at 320 nm, 410 nm, 560 nm, and 630 nm, respectively, at room temperature. The intensity and the wavelength position of PL are dependent on annealing temperature (Ta), and the luminescent mechanism is analyzed.展开更多
The optical properties of LaCl3：Ce crystal are reported in this paper. Optical transmission spectrum, photoluminescence and time resolved photoluminescence spectra at different temperatures are investigated. It is fo...The optical properties of LaCl3：Ce crystal are reported in this paper. Optical transmission spectrum, photoluminescence and time resolved photoluminescence spectra at different temperatures are investigated. It is found that optical transmittance is as high as 80% between 320 nm and 600 nm, and no obvious absorption band is found in this region. Emission intensity and decay time of photoluminescence are quite stable with the change of the temperature between 80 K and 500 K. No thermal quenching is present up to 500 K, and decay time keeps at 17±2 ns. With the increase of the temperature, the whole emission bands and excitation bands present broadening and overlapping, leading to the strengthening of re-absorption of the Ce^3＋ emission, which makes the emission spectra have a red shift trend.展开更多
The relationship between the photothermal cooling efficiency of a micro-cantilever＇s mechanical mode and the en- vironmental temperature is studied. The micro-cantilever and a polished fiber end form a low finesse Fa...The relationship between the photothermal cooling efficiency of a micro-cantilever＇s mechanical mode and the en- vironmental temperature is studied. The micro-cantilever and a polished fiber end form a low finesse Fabry-Perot （FP） cavity. Experimental results in a temperature range from 77 K to 298 K show that temperature has an obvious influence on photothermal cooling efficiency. The photothermal cooling efficiency, ηph, at 100 K is 10 times that at 298 K. This accords well with the theoretical analysis that the high photothermal cooling efficiency can be achieved when photothermal response time, τph, and mechanical resonant frequency, ω0, are close to the optimal photothermal cooling condition ω0τph = 1. Our study provides an important approach for high effective photothermal cooling and high-sensitivity measurement for force microscopy.展开更多
Fluorescence spectra of ladderlike polyphenylsilsesquioxane (LPPS) and ladderlike 1,4-phenylene-bridged polyvinylsiloxane (LPPVS) have been measured as a function of temperature (4-55 degreesC), in dilute tetrahydrofu...Fluorescence spectra of ladderlike polyphenylsilsesquioxane (LPPS) and ladderlike 1,4-phenylene-bridged polyvinylsiloxane (LPPVS) have been measured as a function of temperature (4-55 degreesC), in dilute tetrahydrofuran solution. The excimer (IF) to monomer (I-M) intensity ratio (I-E/I-M) of LPPS dilute solution shows a double linear Arrhenius plot with a break point ascribable to a transition temperature Tt. This behavior has not been found for single chain polyorganosiloxanes. When In/(E) of LPPS was plotted against 1/T, it also gave a double linear plot with one break point, which was found in single chain polyorganosiloxanes. The different behaviors between LPPS and single chain polyorganosiloxanes may be mainly attributed to the relatively rigid double-chain macromolecular backbone of LPPS. However, the 1n(I-E/I-M) of dilute LPPVS solution versus 1/T shows a simple linear variation with a positive slope which confirms our proposition. The difference between the fluorescence results of LPPS and those of LPPVS may possibly derive from their structure differences and cooperative motion in backbone chain bonds.展开更多
This paper investigates the temperature dependence of single-event transients（SETs） in 90-nm complementary metat-oxide semiconductor（CMOS） dual-well and triple-well negative metal-oxide semiconductor field-effect ...This paper investigates the temperature dependence of single-event transients（SETs） in 90-nm complementary metat-oxide semiconductor（CMOS） dual-well and triple-well negative metal-oxide semiconductor field-effect transistors（NMOSFETs）.Technology computer-aided design（TCAD） three-dimensional（3D） simulations show that the drain current pulse duration increases from 85 ps to 245 ps for triple-well but only increases from 65 ps to 98 ps for dual-well when the temperature increases from-55℃ to 125℃,which is closely correlated with the NMOSFET sources.This reveals that the pulse width increases with temperature in dual-well due to the weakening of the anti-amplification bipolar effect while increases with temperature in triple-well due to the enhancement of the bipolar amplification.展开更多
Triheptyl cellulose/ethyl cellulose(3/97)binary blend membranes were prepared from tetrahydrofuran,chloroform and dichloromethane solutions and their air separation capabit- ities were studied at different temperature...Triheptyl cellulose/ethyl cellulose(3/97)binary blend membranes were prepared from tetrahydrofuran,chloroform and dichloromethane solutions and their air separation capabit- ities were studied at different temperatures.With increasing temperature from 25 to 85℃,the flux QOEA of O_2-enriched air(OEA),O_2 permselectivity and the O_2 concentration Yo_2 in the OEA all increase.The membranes show a unique trend in their Yo_2～QOEA relationship,that is,the air separation capability increases simultaneously with the OEA permeation capability.The magnitudes of QOEA and Yo_2 for 17μm-thick membrane after the testg time of 36hours at 70℃ are 5×10^(-4)cm^3 (STP)/s·cm^2 and 37.6%,respectively.The air separation capability depends slightly on membrane forming solvents.展开更多
Two kinds of InAs/GaAs quantum dot（QD） structures are grown by molecular beam epitaxy in formation–dissolution–regrowth method with different in-situ annealing and regrowth processes. The densities and sizes of qu...Two kinds of InAs/GaAs quantum dot（QD） structures are grown by molecular beam epitaxy in formation–dissolution–regrowth method with different in-situ annealing and regrowth processes. The densities and sizes of quantum dots are different for the two samples. The variation tendencies of PL peak energy, integrated intensity, and full width at half maximum versus temperature for the two samples are analyzed, respectively. We find the anomalous temperature dependence of the InAs/GaAs quantum dots and compare it with other previous reports. We propose a new energy band model to explain the phenomenon. We obtain the activation energy of the carrier through the linear fitting of the Arrhenius curve in a high temperature range. It is found that the Ga As barrier layer is the major quenching channel if there is no defect in the material. Otherwise, the defects become the major quenching channel when some defects exist around the QDs.展开更多
We report the temperature dependence of the spin pumping effect for Y_(3)Fe_(5)O_(12)(YIG,0.9μm)/NiO(tNiO)/W(6 nm)(tNiO=0 nm,1 nm,2 nm,and 10 nm)heterostructures.All samples exhibit a strong temperature-dependent inv...We report the temperature dependence of the spin pumping effect for Y_(3)Fe_(5)O_(12)(YIG,0.9μm)/NiO(tNiO)/W(6 nm)(tNiO=0 nm,1 nm,2 nm,and 10 nm)heterostructures.All samples exhibit a strong temperature-dependent inverse spin Hall effect(ISHE)signal I_(c)and sensitivity to the NiO layer thickness.We observe a dramatic decrease of I_(c)with inserting thin NiO layer between YIG and W layers indicating that the inserting of NiO layer significantly suppresses the spin transport from YIG to W.In contrast to the noticeable enhancement in YIG/NiO(tNiO≈1-2 nm)/Pt,the suppression of spin transport may be closely related to the specific interface-dependent spin scattering,spin memory loss,and spin conductance at the NiO/W interface.Besides,the I_(c)of YIG/Ni O/W exhibits a maximum near the TNof the AF NiO layer because the spins are transported dominantly by incoherent thermal magnons.展开更多
The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. ...The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO3 and SO2 in air is higher at 500-1 100 ℃ and lower at 1 200 ℃ compared with that in O2/CO2 atmosphere. The conversion can be increased by increasing the concentration of SO2, which causes the inhibition of CaSO4 decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO3 and SO2 differs with temperature in O2/CO2 atmosphere, i.e. CaCO3 directly reacts with SO2 at 500 ℃ and CaO from CaCO3 decomposition reacts with SO2 at 1 000 ℃. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 ℃ in O2/CO2 atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.展开更多
The influence of temperature on mode coupling effect in piezoelectric vibrators remains unclear.In this work,we discuss the influence of temperature on two-dimensional(2D)mode coupling effect and electromechanical cou...The influence of temperature on mode coupling effect in piezoelectric vibrators remains unclear.In this work,we discuss the influence of temperature on two-dimensional(2D)mode coupling effect and electromechanical coupling coefficient of cylindrical[001]c-poled Mn-doped 0.24PIN-0.46PMN-0.30PT piezoelectric single-crystal vibrator with an arbitrary configuration ratio.The electromechanical coupling coefficient kt decreases with temperature increasing,whereas k33 is largely invariant in a temperature range of 25℃-55℃.With the increase of temperature,the shift in the‘mode dividing point’increases the scale of the poling direction of the piezoelectric vibrator.The temperature has little effect on coupling constantΓ.At a given temperature,the coupling constantΓof the cylindrical vibrator is slightly greater than that of the rectangular vibrator.When the temperature changes,the applicability index(M)values of the two piezoelectric vibrators are close to 1,indicating that the coupling theory can be applied to piezoelectric vibrators made of late-model piezoelectric single crystals.展开更多
This paper presents an analysis of the local electric field in hexagonal boron nitride （h-BN） by introducing a modified parameter. Based on the determination of the modified parameter of h-BN, the revised Lorenz equ...This paper presents an analysis of the local electric field in hexagonal boron nitride （h-BN） by introducing a modified parameter. Based on the determination of the modified parameter of h-BN, the revised Lorenz equation is developed. Then the permittivity at high temperature and in the microwave frequency is investigated. In addition, this equation is derived for evaluating the temperature coefficient of the permittivity of h-BN. The analyses show that the permittivity increases with increasing temperature, which is mainly attributed to the positive temperature coefficient of the ionic polarizability.展开更多
文摘We study the influences of the temperature on the energy-band structure for the Holstein molecular-crystal model. We show that the energy-band width and the energy-gap width of a solid are relevant to both the interaction between an electron and thermal phonons and to thermal expansion. For a one-dimensional Li atom lattice chain, under the chosen parameters,the width of the ls and 2s energy bands narrows as the temperature increases and the energy-gap width between the two bands widens. These results agree qualitatively with those observed experimentally. Studying temperature dependence of the energy-band structure is of great importance for understanding optical and transporting characteristics of a solid.
文摘The temperature dependence of some performance of 6H SiC unipolar power devices is analyzed theoretically.By employing the temperature dependent ionization coefficient and mobility of a silicon carbide,the analytical expressions of the temperature dependent performance,such as breakdown characteristics and on resistance of 6H SiC unipolar power devices are derived in a closed form.The analytical results are compared with the experimental results,with good accordance found in the breakdown characteristics.
基金Project supported by the Doctoral Fund of Ministry of Education of China(Grant No.20111103120016)the State Grid Corporation of China Program of Science and Technology,China(Grant No.5455DW140003)
文摘The temperature dependences of forward voltage drop（VF） of the fast recovery diodes（FRDs） are remarkably influenced by different lifetime controlled treatments. In this paper the results of an experimental study are presented, which are the lifetime controls of platinum treatment, electron irradiation treatment, and the combined treatment of the above ones.Based on deep level transient spectroscopy（DLTS） measurements, a new level E6（EC-0.376 e V） is found in the combined lifetime treated（CLT） sample, which is different from the levels of the individual platinum and electron irradiation ones. Comparing the tested VFresults of CLT samples with the others, the level E6 is responsible for the degradation of temperature dependence of the forward voltage drop in the FRD.
基金supported partially by the Important National Science&Technology Specific Projects,China(Grant No.2013ZX02503003)
文摘In this work, temperature dependences of small-signal model parameters in the SiGe HBT HICUM model are presented. Electrical elements in the small-signal equivalent circuit are first extracted at each temperature, then the temperature dependences are determined by the series of extracted temperature coefficients, based on the established temperature for- mulas for corresponding model parameters. The proposed method is validated by a 1x 0.2 x 16 μm2 SiGe HBT over a wide temperature range （from 218 K to 473 K）, and good matching is obtained between the extracted and modeled resuits. Therefore, we believe that the proposed extraction flow of model parameter temperature dependence is reliable for characterizing the transistor performance and guiding the circuit design over a wide temperature range.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.60906041,60736033,60890193,and 10774001)
文摘The temperature dependence of carrier transport properties of Alx Gal-xN/InyGal-yN/CaN and AlzGal-xN/GaN heterostructures has been investigated. It is shown that the Hall mobility in Alo.25Gao.75N/Ino.03Gao.97N/GaN heterostructures is higher than that in Alo.25Gao.75N/GaN heterostructures at temperatures above 500 K, even the mobility in the former is much lower than that in the latter at 300 K. More importantly, the electron sheet density in Alo.25Gao.75N/Ino.03Gao.97N/GaN heterostructures decreases slightly, whereas the electron sheet density in Al0.25Gao.75N/CaN heterostructures gradually increases with increasing temperature above 500 K. It is believed that an electron depletion layer is formed due to the negative polarization charges at the Iny Can-yN/GaN heterointerface induced by the compressive strain in the InyCal-yN channel, which effectively suppresses the parallel conductivity originating from the thermal excitation in the underlying GaN layer at high temperatures.
基金Project supported by the Key Program of the National Natural Science Foundation of China(Grant No.60836004)
文摘A comparison of the temperature dependence of the P-hit single event transient （SET） in a two-transistor （2T） inverter with that in a three-transistor （3T） inverter is carried out based on a three-dimensional numerical simulation. Due to the significantly distinct mechanisms of the single event change collection in the 2T and the 3T inverters, the temperature plays different roles in the SET production and propagation. The SET pulse will be significantly broadened in the 2T inverter chain while will be compressed in the 3T inverter chain as temperature increases. The investigation provides a new insight into the SET mitigation under the extreme environment, where both the high temperature and the single event effects should be considered. The 3T inverter layout structure （or similar layout structures） will be a better solution for spaceborne integrated circuit design for extreme environments.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60836004, 61076025, and 61006070)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20104307120006)
文摘Using three-dimensional technology computer-aided design （TCAD） simulation, parasitic bipolar amplification in a single event transient （SET） current of a single transistor and its temperature dependence are studied. We quantify the contributions of different current components in a SET current pulse, and it is found that the proportion of parasitic bipolar amplification in total collected charge is about 30% in both ]30-nm and 90-nm technologies. The temperature dependence of parasitic bipolar amplification and the mechanism of the SET pulse are also investigated and quantified. The results show that the proportion of charge induced by parasitic bipolar increases with rising temperature, which illustrates that the parasitic bipolar amplification plays an important role in the charge collection of a single transistor.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61176085,11474365 and 61377055the Department of Education of Guangdong Province under Grant No gjhz1103the Open-Project Program of the State Key laboratory of Opto-Electronic Material and Technologies of Sun Yatsen University
文摘The microRaman scattering of 4H-SiC films, fabricated by low pressure chemical vapor deposition under different growth conditions, is investigated at temperatures ranging from 80 K to 550K. The effects of growth conditions on E2 （TO）, E1 （TO） and A1 （LO） phonon mode frequencies are negligible. The temperature dependences of phonon linewidth and lifetime of E2 （TO） modes are analyzed in terms of an anharmonic damping effect induced by thermal and growth conditions. The results show that the lifetime of E2 （TO） mode increases when the quality of the sample improves. Unlike other phone modes, Raman shift of A1 （longitudinal optical plasma coupling （LOPC）） mode does not decrease monotonously when the temperature increases, but tends to blueshift at low temperatures and to redshift at relatively high temperatures. Theoretical analyses are given for the abnormal phenomena of A1 （LOPC） mode in 4H-SiC.
文摘Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows dependence on temperature, as well as, level of doping. The conductivity is considered to be due to thermal hopping motion of localized charge carriers,which are believed to be polarons, in the temperature range 303 K to 323 K and for T>343 K,whereas. it is metal-like in the temperature range 323 K to 343 K
文摘The silicon-rich silica films were prepared by a dual-ion-beam co-sputtering method from a composite Target in an argon atmosphere. The structure of the films studied by the aid of TEM and XRD is amorphous. The photoluminescence (PL) spectra were found to have a 4- luminescent band peak at 320 nm, 410 nm, 560 nm, and 630 nm, respectively, at room temperature. The intensity and the wavelength position of PL are dependent on annealing temperature (Ta), and the luminescent mechanism is analyzed.
文摘The optical properties of LaCl3：Ce crystal are reported in this paper. Optical transmission spectrum, photoluminescence and time resolved photoluminescence spectra at different temperatures are investigated. It is found that optical transmittance is as high as 80% between 320 nm and 600 nm, and no obvious absorption band is found in this region. Emission intensity and decay time of photoluminescence are quite stable with the change of the temperature between 80 K and 500 K. No thermal quenching is present up to 500 K, and decay time keeps at 17±2 ns. With the increase of the temperature, the whole emission bands and excitation bands present broadening and overlapping, leading to the strengthening of re-absorption of the Ce^3＋ emission, which makes the emission spectra have a red shift trend.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB922101)
文摘The relationship between the photothermal cooling efficiency of a micro-cantilever＇s mechanical mode and the en- vironmental temperature is studied. The micro-cantilever and a polished fiber end form a low finesse Fabry-Perot （FP） cavity. Experimental results in a temperature range from 77 K to 298 K show that temperature has an obvious influence on photothermal cooling efficiency. The photothermal cooling efficiency, ηph, at 100 K is 10 times that at 298 K. This accords well with the theoretical analysis that the high photothermal cooling efficiency can be achieved when photothermal response time, τph, and mechanical resonant frequency, ω0, are close to the optimal photothermal cooling condition ω0τph = 1. Our study provides an important approach for high effective photothermal cooling and high-sensitivity measurement for force microscopy.
基金The authors gratefully thank the National Natural Science Foundation of China (No. 29874034, 29992530, 29873060) and Dow Corning Corporation for their financial support.
文摘Fluorescence spectra of ladderlike polyphenylsilsesquioxane (LPPS) and ladderlike 1,4-phenylene-bridged polyvinylsiloxane (LPPVS) have been measured as a function of temperature (4-55 degreesC), in dilute tetrahydrofuran solution. The excimer (IF) to monomer (I-M) intensity ratio (I-E/I-M) of LPPS dilute solution shows a double linear Arrhenius plot with a break point ascribable to a transition temperature Tt. This behavior has not been found for single chain polyorganosiloxanes. When In/(E) of LPPS was plotted against 1/T, it also gave a double linear plot with one break point, which was found in single chain polyorganosiloxanes. The different behaviors between LPPS and single chain polyorganosiloxanes may be mainly attributed to the relatively rigid double-chain macromolecular backbone of LPPS. However, the 1n(I-E/I-M) of dilute LPPVS solution versus 1/T shows a simple linear variation with a positive slope which confirms our proposition. The difference between the fluorescence results of LPPS and those of LPPVS may possibly derive from their structure differences and cooperative motion in backbone chain bonds.
基金Project supported by the State Key Program of the National Natural Science Foundation of China (Grant No. 60836004)Innovation Foundation for Postgraduate of Hunan Province,China (Grant No. CX2011B026)
文摘This paper investigates the temperature dependence of single-event transients（SETs） in 90-nm complementary metat-oxide semiconductor（CMOS） dual-well and triple-well negative metal-oxide semiconductor field-effect transistors（NMOSFETs）.Technology computer-aided design（TCAD） three-dimensional（3D） simulations show that the drain current pulse duration increases from 85 ps to 245 ps for triple-well but only increases from 65 ps to 98 ps for dual-well when the temperature increases from-55℃ to 125℃,which is closely correlated with the NMOSFET sources.This reveals that the pulse width increases with temperature in dual-well due to the weakening of the anti-amplification bipolar effect while increases with temperature in triple-well due to the enhancement of the bipolar amplification.
文摘Triheptyl cellulose/ethyl cellulose(3/97)binary blend membranes were prepared from tetrahydrofuran,chloroform and dichloromethane solutions and their air separation capabit- ities were studied at different temperatures.With increasing temperature from 25 to 85℃,the flux QOEA of O_2-enriched air(OEA),O_2 permselectivity and the O_2 concentration Yo_2 in the OEA all increase.The membranes show a unique trend in their Yo_2～QOEA relationship,that is,the air separation capability increases simultaneously with the OEA permeation capability.The magnitudes of QOEA and Yo_2 for 17μm-thick membrane after the testg time of 36hours at 70℃ are 5×10^(-4)cm^3 (STP)/s·cm^2 and 37.6%,respectively.The air separation capability depends slightly on membrane forming solvents.
基金supported by the National Basic Research Program of China(Grant No.2013CB632104)the National Key Research and Development Program of China(Grant No.2016YFB0402302)
文摘Two kinds of InAs/GaAs quantum dot（QD） structures are grown by molecular beam epitaxy in formation–dissolution–regrowth method with different in-situ annealing and regrowth processes. The densities and sizes of quantum dots are different for the two samples. The variation tendencies of PL peak energy, integrated intensity, and full width at half maximum versus temperature for the two samples are analyzed, respectively. We find the anomalous temperature dependence of the InAs/GaAs quantum dots and compare it with other previous reports. We propose a new energy band model to explain the phenomenon. We obtain the activation energy of the carrier through the linear fitting of the Arrhenius curve in a high temperature range. It is found that the Ga As barrier layer is the major quenching channel if there is no defect in the material. Otherwise, the defects become the major quenching channel when some defects exist around the QDs.
基金support from the National Natural Science Foundation of China(Grant Nos.11774160,61427812,61805116,12004171,61774081,and 62171096)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20192006)+4 种基金the National Key Scientific Instrument and Equipment Development Project of China(Grant No.51827802)the Natural Science Foundation of Jiangsu Province of China(Grant Nos.BK20180056 and BK20200307)the Applied Basic Research Programs of the Science and Technology Commission Foundation of Jiangsu Province,China(Grant No.BK20200309)the Open Research Fund of Jiangsu Provincial Key Laboratory for Nanotechnology,the Scientific Foundation of Nanjing University of Posts and Telecommunications(NUPTSF)(Grant No.NY220164)the State Key R&D Project of Guangdong,China(Grant No.2020B010174002)
文摘We report the temperature dependence of the spin pumping effect for Y_(3)Fe_(5)O_(12)(YIG,0.9μm)/NiO(tNiO)/W(6 nm)(tNiO=0 nm,1 nm,2 nm,and 10 nm)heterostructures.All samples exhibit a strong temperature-dependent inverse spin Hall effect(ISHE)signal I_(c)and sensitivity to the NiO layer thickness.We observe a dramatic decrease of I_(c)with inserting thin NiO layer between YIG and W layers indicating that the inserting of NiO layer significantly suppresses the spin transport from YIG to W.In contrast to the noticeable enhancement in YIG/NiO(tNiO≈1-2 nm)/Pt,the suppression of spin transport may be closely related to the specific interface-dependent spin scattering,spin memory loss,and spin conductance at the NiO/W interface.Besides,the I_(c)of YIG/Ni O/W exhibits a maximum near the TNof the AF NiO layer because the spins are transported dominantly by incoherent thermal magnons.
基金Project(50525619) supported by the National Natural Science Foundation of ChinaProject(306012) supported by the Key Foundation of Ministry of Education of China
文摘The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO3 and SO2 in air is higher at 500-1 100 ℃ and lower at 1 200 ℃ compared with that in O2/CO2 atmosphere. The conversion can be increased by increasing the concentration of SO2, which causes the inhibition of CaSO4 decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO3 and SO2 differs with temperature in O2/CO2 atmosphere, i.e. CaCO3 directly reacts with SO2 at 500 ℃ and CaO from CaCO3 decomposition reacts with SO2 at 1 000 ℃. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 ℃ in O2/CO2 atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.
基金Project supported by the Basic Scientific Research Foundation of College and University in Heilongjiang Province,China(Grant No.2018QNL-16)the Guiding Science and Technology Project of Daqing City(GSTPDQ),China(Grant No.zd-2019-03)the National Natural Science Foundation of China(Grant Nos.11304061 and 51572056).
文摘The influence of temperature on mode coupling effect in piezoelectric vibrators remains unclear.In this work,we discuss the influence of temperature on two-dimensional(2D)mode coupling effect and electromechanical coupling coefficient of cylindrical[001]c-poled Mn-doped 0.24PIN-0.46PMN-0.30PT piezoelectric single-crystal vibrator with an arbitrary configuration ratio.The electromechanical coupling coefficient kt decreases with temperature increasing,whereas k33 is largely invariant in a temperature range of 25℃-55℃.With the increase of temperature,the shift in the‘mode dividing point’increases the scale of the poling direction of the piezoelectric vibrator.The temperature has little effect on coupling constantΓ.At a given temperature,the coupling constantΓof the cylindrical vibrator is slightly greater than that of the rectangular vibrator.When the temperature changes,the applicability index(M)values of the two piezoelectric vibrators are close to 1,indicating that the coupling theory can be applied to piezoelectric vibrators made of late-model piezoelectric single crystals.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50902017)the Scientific Research Fund of Sichuan Provincial Education Department, China (Grant No. 09ZC029)
文摘This paper presents an analysis of the local electric field in hexagonal boron nitride （h-BN） by introducing a modified parameter. Based on the determination of the modified parameter of h-BN, the revised Lorenz equation is developed. Then the permittivity at high temperature and in the microwave frequency is investigated. In addition, this equation is derived for evaluating the temperature coefficient of the permittivity of h-BN. The analyses show that the permittivity increases with increasing temperature, which is mainly attributed to the positive temperature coefficient of the ionic polarizability.
