We study the spin-dependent thermopower in a double-quantum-dot(DQD) embedded between the left and right two-dimensional electron gases(2DEGs) in doped quantum wells under an in-plane magnetic field. When the separati...We study the spin-dependent thermopower in a double-quantum-dot(DQD) embedded between the left and right two-dimensional electron gases(2DEGs) in doped quantum wells under an in-plane magnetic field. When the separation between the DQD is smaller than the Fermi wavelength in the 2DEGs, the asymmetry in the dots' energy levels leads to pronounced quantum interference effects characterized by the Dicke line-shape of the conductance, which are sensitive to the properties of the 2DEGs. The magnitude of the thermopower, which denotes the generated voltage in response to an infinitesimal temperature difference between the two 2DEGs under vanishing charge current, will be obviously enhanced by the Dicke effect. The application of the in-plane magnetic field results in the polarization of the spin-up and spin-down conductances and thermopowers, and enables an efficient spin-filter device in addition to a tunable pure spin thermopower in the absence of its charge counterpart.展开更多
Based on the Green＇s function technique and the equation of motion approach, this paper theoretically studies the thermoelectric effect in parallel coupled double quantum dots （DQDs）, in which Rashba spin-orbit int...Based on the Green＇s function technique and the equation of motion approach, this paper theoretically studies the thermoelectric effect in parallel coupled double quantum dots （DQDs）, in which Rashba spin-orbit interaction is taken into account. Rashba spin^rbit interaction contributions, even in a magnetic field, are exhibited obviously in the double quantum dots system for the thermoelectric effect. The periodic oscillation of thermopower can be controlled by tunning the Rashba spin^rbit interaction induced phase. The interesting spin-dependent thermoelectric effects will arise which has important influence on thermoelectric properties of the studied system.展开更多
Effects of nonparabolicity of energy band on thermopower, in-plane effective mass and Fermi energy are inves- tigated in size-quantized semiconductor films in a strong while non-quantized magnetic field. We obtain the...Effects of nonparabolicity of energy band on thermopower, in-plane effective mass and Fermi energy are inves- tigated in size-quantized semiconductor films in a strong while non-quantized magnetic field. We obtain the expressions of these quantities as functions of thickness, concentration and nonparabolicity parameter. The influence of nonparabolicity is studied for degenerate and non-degenerate electron gases, and it is shown that nonparabolicity changes the character of thickness and the concentration dependence of thermopower, in-plane effective mass and Fermi energy. Moreover, the magnitudes of these quantities significantly increase with respect to the nonparabolicity parameter in the case of strong nonparabolicity in nano-films. The concentration depen- dence is also studied, and it is shown that thermopower increases when the concentration decreases. These results are in agreement with the experimental data.展开更多
Ionic thermoelectrics(i-TE) possesses great potential in powering distributed electronics because it can generate thermopower up to tens of millivolts per Kelvin. However,as ions cannot enter external circuit, the uti...Ionic thermoelectrics(i-TE) possesses great potential in powering distributed electronics because it can generate thermopower up to tens of millivolts per Kelvin. However,as ions cannot enter external circuit, the utilization of i-TE is currently based on capacitive charge/discharge, which results in discontinuous working mode and low energy density. Here,we introduce an ion–electron thermoelectric synergistic(IETS)effect by utilizing an ion–electron conductor. Electrons/holes can drift under the electric field generated by thermodiffusion of ions, thus converting the ionic current into electrical current that can pass through the external circuit. Due to the IETS effect, i-TE is able to operate continuously for over 3000 min.Moreover, our i-TE exhibits a thermopower of 32.7 mV K^(-1) and an energy density of 553.9 J m^(-2), which is more than 6.9 times of the highest reported value. Consequently, direct powering of electronics is achieved with i-TE. This work provides a novel strategy for the design of high-performance i-TE materials.展开更多
Indium selenide （InSe） thin films have been prepared by e-beam technique onto glass substrate at a pressure of-8 × 10^-5 Pa. The deposition rate of the InSe thin films is -8.30 nms^-1. InSe samples grown at roo...Indium selenide （InSe） thin films have been prepared by e-beam technique onto glass substrate at a pressure of-8 × 10^-5 Pa. The deposition rate of the InSe thin films is -8.30 nms^-1. InSe samples grown at room temperature have been termed as virgin, whereas the films at which the transition in electrical conductivity is shown to exhibit at a temperature of 415 to 455 K have been termed as phase-transited samples. X-ray diffraction （XRD） study reveals that lnSe thin films are amorphous in nature before phase-transition while they are polycrystalline after phase-transition. Scanning electron microscopy （SEM） has been used to study the surface morphology of InSe thin films. Before phase-transition grains are absent in the films and surfaces are almost smooth and uniform. Film surfaces are seen to exhibit a number of grains after phase-transition and they are rough in surfaces. The elemental composition of the lnSe thin films has been estimated by EDAX method. The effects of temperature on the electrical properties of InSe thin films have been studied in details. Temperature dependence of electrical conductivity shows a semiconducting behavior with activation energy. Thickness dependence of conductivity is well in conformity with the Fuchs-Sondheimer theory. Thermopower study indicates that the InSe film is an n-type semiconductor. The optical study of InSe thin films is carried out in the wavelength range 360 to 1100 nm at room temperature. The study of absorption coefficient of InSe thin films shows a direct type transition with a band gap of=1.65 eV which is well agreed with the reported values. Integrated values of luminous and solar transmittance as well as of reflectance have been calculated. Appreciable order of transmittance and reflectance suggest that this material is a potential candidate for the application in selective surface devices.展开更多
We investigate the nonlinear thermal transport properties of a single interacting quantum dot with two energy levels tunnel-coupled to two electrodes using nonequilibrium Green function method and Hartree-Fock decoupl...We investigate the nonlinear thermal transport properties of a single interacting quantum dot with two energy levels tunnel-coupled to two electrodes using nonequilibrium Green function method and Hartree-Fock decoupling approximation. In the case of asymmetric tunnel-couplings to two electrodes, for example, when the upper level of the quantum dot is open for transport, whereas the lower level is blocked, our calculations predict a strong asymmetry for the heat （energy） current, which shows that the quantum dot system may act as a thermal rectifier in this specific situation.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61274101,51362031,and 11675023)the Innovation Development Fund of China Academy of Engineering Physics(CAEP)(Grant No.ZYCX1921-02)+2 种基金the Presidential Foundation of CAEP(Grant No.YZ2015014)the Initial Project of University of Electronic Science and Technology of China,Zhongshan Institute(Grant No.415YKQ02)Science and Technology Bureau of Zhongshan,China(Grant Nos.417S26 and 180809162197886)
文摘We study the spin-dependent thermopower in a double-quantum-dot(DQD) embedded between the left and right two-dimensional electron gases(2DEGs) in doped quantum wells under an in-plane magnetic field. When the separation between the DQD is smaller than the Fermi wavelength in the 2DEGs, the asymmetry in the dots' energy levels leads to pronounced quantum interference effects characterized by the Dicke line-shape of the conductance, which are sensitive to the properties of the 2DEGs. The magnitude of the thermopower, which denotes the generated voltage in response to an infinitesimal temperature difference between the two 2DEGs under vanishing charge current, will be obviously enhanced by the Dicke effect. The application of the in-plane magnetic field results in the polarization of the spin-up and spin-down conductances and thermopowers, and enables an efficient spin-filter device in addition to a tunable pure spin thermopower in the absence of its charge counterpart.
基金supported by the Scientific Research Fund of Heilongjiang Provincial Education Department of China (GrantNo. 11551145)
文摘Based on the Green＇s function technique and the equation of motion approach, this paper theoretically studies the thermoelectric effect in parallel coupled double quantum dots （DQDs）, in which Rashba spin-orbit interaction is taken into account. Rashba spin^rbit interaction contributions, even in a magnetic field, are exhibited obviously in the double quantum dots system for the thermoelectric effect. The periodic oscillation of thermopower can be controlled by tunning the Rashba spin^rbit interaction induced phase. The interesting spin-dependent thermoelectric effects will arise which has important influence on thermoelectric properties of the studied system.
文摘Effects of nonparabolicity of energy band on thermopower, in-plane effective mass and Fermi energy are inves- tigated in size-quantized semiconductor films in a strong while non-quantized magnetic field. We obtain the expressions of these quantities as functions of thickness, concentration and nonparabolicity parameter. The influence of nonparabolicity is studied for degenerate and non-degenerate electron gases, and it is shown that nonparabolicity changes the character of thickness and the concentration dependence of thermopower, in-plane effective mass and Fermi energy. Moreover, the magnitudes of these quantities significantly increase with respect to the nonparabolicity parameter in the case of strong nonparabolicity in nano-films. The concentration depen- dence is also studied, and it is shown that thermopower increases when the concentration decreases. These results are in agreement with the experimental data.
基金financially supported by research grants from the Natural Science Foundation of China [Grant No. 62074022 (K.S.), 12004057 (Y.J.Z.), 52173235 (M.L.)]the Natural Science Foundation of Chongqing [cstc2021jcyj-jqX0015 (K.S.)]+3 种基金Chongqing Talent Plan [cstc2021ycjh-bgzxm0334 (S.S.C.), CQYC2021059206 (K.S.)]Fundamental Research Funds for the Central Universities [No. 2020CDJQY-A055 (K.S.)]the Key Laboratory of Low-grade Energy Utilization Technologies and Systems [Grant No. LLEUTS-201901 (K.S.)]support from Chongqing Postgraduate Research and Innovation Project (CYS22032)。
文摘Ionic thermoelectrics(i-TE) possesses great potential in powering distributed electronics because it can generate thermopower up to tens of millivolts per Kelvin. However,as ions cannot enter external circuit, the utilization of i-TE is currently based on capacitive charge/discharge, which results in discontinuous working mode and low energy density. Here,we introduce an ion–electron thermoelectric synergistic(IETS)effect by utilizing an ion–electron conductor. Electrons/holes can drift under the electric field generated by thermodiffusion of ions, thus converting the ionic current into electrical current that can pass through the external circuit. Due to the IETS effect, i-TE is able to operate continuously for over 3000 min.Moreover, our i-TE exhibits a thermopower of 32.7 mV K^(-1) and an energy density of 553.9 J m^(-2), which is more than 6.9 times of the highest reported value. Consequently, direct powering of electronics is achieved with i-TE. This work provides a novel strategy for the design of high-performance i-TE materials.
文摘Indium selenide （InSe） thin films have been prepared by e-beam technique onto glass substrate at a pressure of-8 × 10^-5 Pa. The deposition rate of the InSe thin films is -8.30 nms^-1. InSe samples grown at room temperature have been termed as virgin, whereas the films at which the transition in electrical conductivity is shown to exhibit at a temperature of 415 to 455 K have been termed as phase-transited samples. X-ray diffraction （XRD） study reveals that lnSe thin films are amorphous in nature before phase-transition while they are polycrystalline after phase-transition. Scanning electron microscopy （SEM） has been used to study the surface morphology of InSe thin films. Before phase-transition grains are absent in the films and surfaces are almost smooth and uniform. Film surfaces are seen to exhibit a number of grains after phase-transition and they are rough in surfaces. The elemental composition of the lnSe thin films has been estimated by EDAX method. The effects of temperature on the electrical properties of InSe thin films have been studied in details. Temperature dependence of electrical conductivity shows a semiconducting behavior with activation energy. Thickness dependence of conductivity is well in conformity with the Fuchs-Sondheimer theory. Thermopower study indicates that the InSe film is an n-type semiconductor. The optical study of InSe thin films is carried out in the wavelength range 360 to 1100 nm at room temperature. The study of absorption coefficient of InSe thin films shows a direct type transition with a band gap of=1.65 eV which is well agreed with the reported values. Integrated values of luminous and solar transmittance as well as of reflectance have been calculated. Appreciable order of transmittance and reflectance suggest that this material is a potential candidate for the application in selective surface devices.
基金Supported by the National Natural Science Foundation of China, the Shanghai Municipal Commission of Science and Technology, the Shanghai Pujiang Programme, and the Programme for New Century Excellent Talents in University （NCET）.
文摘We investigate the nonlinear thermal transport properties of a single interacting quantum dot with two energy levels tunnel-coupled to two electrodes using nonequilibrium Green function method and Hartree-Fock decoupling approximation. In the case of asymmetric tunnel-couplings to two electrodes, for example, when the upper level of the quantum dot is open for transport, whereas the lower level is blocked, our calculations predict a strong asymmetry for the heat （energy） current, which shows that the quantum dot system may act as a thermal rectifier in this specific situation.
