The objective of this study is to find an effective method to improve Voc without Jsc loss for Cu2ZnSnSe4 （CZTSe） thin film solar cells, which have been fabricated by the one step co-evaporation technique. Surface s...The objective of this study is to find an effective method to improve Voc without Jsc loss for Cu2ZnSnSe4 （CZTSe） thin film solar cells, which have been fabricated by the one step co-evaporation technique. Surface sulfurization of CZTSe thin films is carried out by using one technique that does not utilize toxic H2S gas; a sequential evaporation of SnS after CZTSe deposition and the annealing of CZTSe thin films in selenium vapor. A Cu2ZnSn（S, Se）4 （CZTSSe） thin layer is grown on the surface of the CZTSe thin film after the annealing. The conversion efficiency of the completed device is improved due to the enhancement of Voc, which could be attributed to the formation of a hole-recombination barrier at the surface or the passivation of the surface and grain boundary by S incorporation.展开更多
Non-thermal plasma surface modification for epoxy resin（EP）to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulatedtransmission line.In this paper,a pulsed Ar...Non-thermal plasma surface modification for epoxy resin（EP）to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulatedtransmission line.In this paper,a pulsed Ar dual dielectrics atmospheric-pressure plasma jet（APPJ）was used for Si CxHyOzthin film deposition on EP samples.The film deposition was optimized by varying the treatment time while other parameters were kept at constants（treatment distance：10 mm,precursor flow rate：0.6 l min-（-1）,maximum instantaneous power：3.08 k W and single pulse energy：0.18 m J）.It was found that the maximum value of flashover voltages for negative and positive voltage were improved by 18%and 13%when the deposition time was3 min,respectively.The flashover voltage reduced as treatment time increased.Moreover,all the surface conductivity,surface charge dissipation rate and surface trap level distribution reached an optimal value when thin film deposition time was 3 min.Other measurements,such as atomic force microscopy and scanning electron microscope for EP surface morphology,Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy for EP surface compositions,optical emission spectra for APPJ deposition process were carried out to better understand the deposition processes and mechanisms.The results indicated that the original organic groups（C–H,C–C,C=O,C=C）were gradually replaced by the Si containing inorganic groups（Si–O–Si and Si–OH）.The reduction of C=O in ester group and C=C in p-substituted benzene of the EP samples might be responsible for shallowing the trap level and then enhancing the flashover voltage.However,when the plasma treatment time was longer than 3 min,the significant increase of the surface roughness might increase the trap level depth and then deteriorate the flashover performance.展开更多
The gas-solid interfaces formed by solid insulation and gas atmosphere are weak links in the insulation of electrical equipment.They are prone to surface flashover or breakdown,leading to accidents that severely affec...The gas-solid interfaces formed by solid insulation and gas atmosphere are weak links in the insulation of electrical equipment.They are prone to surface flashover or breakdown,leading to accidents that severely affect the safe and stable operation of power systems.In recent years,the construction of dielectric functionally graded insulation(d-FGI)has become an effective solution to address this issue.This paper employs an iterative algorithm to optimize the spatial distribution of permittivity for d-FGIs in truncated cone insulators and analyzes the comprehensive influence of various parameters on the electric-field optimization effect.The optimization results show that the maximum surface electric-field strength of the graded insulators can be reduced by over 70%under ideal conditions,indicating a significant optimization effect.Photosensitive resin-based dielectric-grade insulators were prepared using stereolithography 3D printing technology.Flashover voltage tests were conducted on the photosensitive resin-based graded insulator samples.The results demonstrate that under 0.4 MPa SF_(6) gas,the flashover voltage of photosensitive resin-based dielectric graded insulators can be increased by up to 22.46%compared to pure photosensitive resin insulators,showing a notable improvement in electrical performance.展开更多
An analytical model for the subthreshold current of a strained-Si metal-oxide-semiconductor field-effect transistor (MOSFET) is developed by solving the two-dimensional (2D) Poisson equation and the conventional drift...An analytical model for the subthreshold current of a strained-Si metal-oxide-semiconductor field-effect transistor (MOSFET) is developed by solving the two-dimensional (2D) Poisson equation and the conventional drift-diffusion theory. Model verification is carried out using the 2D device simulator ISE. Good agreement is obtained between the model's calculations and the simulated results. By analyzing the model, the dependence of current on the strained-Si layer strain, doping concentration, source/drain junction depths and substrate voltage is studied. This subthreshold current model provides valuable information for strained-Si MOSFET design.展开更多
In this study,a possible method of reducing the flashover stress is achieved by the effect of an additional magnetic field in the transverse direction on the main applied electric field.The degree of vacuum used in th...In this study,a possible method of reducing the flashover stress is achieved by the effect of an additional magnetic field in the transverse direction on the main applied electric field.The degree of vacuum used in this study was 5×10^(5) Pa.The magnetic flux density B employed in this study extends from 4×10^(3) to 24×10^(3) T.From the results obtained throughout this work,the transverse magnetic field increases the flashover voltage and decreases the leakage current.The effect of the transverse magnetic field on the surface flashover of the dielectric solid in vacuum shows a marked dependence on the material and the thickness of the test specimen,the vacuum degree,the type of electric field(AC or DC)as well as the type of magnetic field(AC or DC).展开更多
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20120031110039
文摘The objective of this study is to find an effective method to improve Voc without Jsc loss for Cu2ZnSnSe4 （CZTSe） thin film solar cells, which have been fabricated by the one step co-evaporation technique. Surface sulfurization of CZTSe thin films is carried out by using one technique that does not utilize toxic H2S gas; a sequential evaporation of SnS after CZTSe deposition and the annealing of CZTSe thin films in selenium vapor. A Cu2ZnSn（S, Se）4 （CZTSSe） thin layer is grown on the surface of the CZTSe thin film after the annealing. The conversion efficiency of the completed device is improved due to the enhancement of Voc, which could be attributed to the formation of a hole-recombination barrier at the surface or the passivation of the surface and grain boundary by S incorporation.
基金supported by National Natural Science Foundation of China under contract No.11575194the National Basic Research Program of China(973 Project) under contract No.2014CB239505-3+2 种基金Natural Science Foundation of Hebei Province under contract No.E2015502081the Fundamental Research Funds for the Central Universities under contract No.2016ZZD07the Young Scholar of the Chang Jiang Scholars Program,Ministry of Education,China
文摘Non-thermal plasma surface modification for epoxy resin（EP）to improve the insulation properties has wide application prospects in gas insulated switchgear and gas insulatedtransmission line.In this paper,a pulsed Ar dual dielectrics atmospheric-pressure plasma jet（APPJ）was used for Si CxHyOzthin film deposition on EP samples.The film deposition was optimized by varying the treatment time while other parameters were kept at constants（treatment distance：10 mm,precursor flow rate：0.6 l min-（-1）,maximum instantaneous power：3.08 k W and single pulse energy：0.18 m J）.It was found that the maximum value of flashover voltages for negative and positive voltage were improved by 18%and 13%when the deposition time was3 min,respectively.The flashover voltage reduced as treatment time increased.Moreover,all the surface conductivity,surface charge dissipation rate and surface trap level distribution reached an optimal value when thin film deposition time was 3 min.Other measurements,such as atomic force microscopy and scanning electron microscope for EP surface morphology,Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy for EP surface compositions,optical emission spectra for APPJ deposition process were carried out to better understand the deposition processes and mechanisms.The results indicated that the original organic groups（C–H,C–C,C=O,C=C）were gradually replaced by the Si containing inorganic groups（Si–O–Si and Si–OH）.The reduction of C=O in ester group and C=C in p-substituted benzene of the EP samples might be responsible for shallowing the trap level and then enhancing the flashover voltage.However,when the plasma treatment time was longer than 3 min,the significant increase of the surface roughness might increase the trap level depth and then deteriorate the flashover performance.
文摘The gas-solid interfaces formed by solid insulation and gas atmosphere are weak links in the insulation of electrical equipment.They are prone to surface flashover or breakdown,leading to accidents that severely affect the safe and stable operation of power systems.In recent years,the construction of dielectric functionally graded insulation(d-FGI)has become an effective solution to address this issue.This paper employs an iterative algorithm to optimize the spatial distribution of permittivity for d-FGIs in truncated cone insulators and analyzes the comprehensive influence of various parameters on the electric-field optimization effect.The optimization results show that the maximum surface electric-field strength of the graded insulators can be reduced by over 70%under ideal conditions,indicating a significant optimization effect.Photosensitive resin-based dielectric-grade insulators were prepared using stereolithography 3D printing technology.Flashover voltage tests were conducted on the photosensitive resin-based graded insulator samples.The results demonstrate that under 0.4 MPa SF_(6) gas,the flashover voltage of photosensitive resin-based dielectric graded insulators can be increased by up to 22.46%compared to pure photosensitive resin insulators,showing a notable improvement in electrical performance.
基金supported by the National Ministries and Commissions (Grant Nos.51308040203 and 6139801)the Fundamental Research Funds for the Central Universities (Grant Nos.72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No.2010JQ8008)
文摘An analytical model for the subthreshold current of a strained-Si metal-oxide-semiconductor field-effect transistor (MOSFET) is developed by solving the two-dimensional (2D) Poisson equation and the conventional drift-diffusion theory. Model verification is carried out using the 2D device simulator ISE. Good agreement is obtained between the model's calculations and the simulated results. By analyzing the model, the dependence of current on the strained-Si layer strain, doping concentration, source/drain junction depths and substrate voltage is studied. This subthreshold current model provides valuable information for strained-Si MOSFET design.
文摘In this study,a possible method of reducing the flashover stress is achieved by the effect of an additional magnetic field in the transverse direction on the main applied electric field.The degree of vacuum used in this study was 5×10^(5) Pa.The magnetic flux density B employed in this study extends from 4×10^(3) to 24×10^(3) T.From the results obtained throughout this work,the transverse magnetic field increases the flashover voltage and decreases the leakage current.The effect of the transverse magnetic field on the surface flashover of the dielectric solid in vacuum shows a marked dependence on the material and the thickness of the test specimen,the vacuum degree,the type of electric field(AC or DC)as well as the type of magnetic field(AC or DC).
