采用微波等离子体化学气相沉积(MWPCVD)技术以不同气源在优化的工艺条件下制备不同类型的金刚石薄膜作为强流脉冲电子发射阴极材料,用SEM、AFM、FTIR和Ram an光谱分析不同金刚石薄膜的组成结构,用2 M eV直线感应型强流电子注入器平台检...采用微波等离子体化学气相沉积(MWPCVD)技术以不同气源在优化的工艺条件下制备不同类型的金刚石薄膜作为强流脉冲电子发射阴极材料,用SEM、AFM、FTIR和Ram an光谱分析不同金刚石薄膜的组成结构,用2 M eV直线感应型强流电子注入器平台检测强流脉冲发射特性。结果表明,不同类型的金刚石薄膜均具有较强的脉冲电子发射能力,发射电流密度均可达70 A/cm2以上;各膜材的发射电流密度和稳定性相差很大,相对而言,以Ar+CO2+CH4+B2H6制备的掺B微米金刚石薄膜能获得的初始电流最大,达到115 A/cm2,其多次脉冲发射稳定性也较好,波动范围在33%以内,且能保证发射电流密度均在84 A/cm2以上,是有希望的强流多脉冲电子发射阴极候选材料。展开更多
具有金属 /绝缘层 /半导体 /金属结构的场助热电子发射阴极是大屏幕显示器中的主要候选部件。电子发射受到各层薄膜的厚度、材料组分和结晶状态等的严重影响。由Au/Ag双层薄膜构成的上电极使得电子亲和势降低0 .5 e V,发射电流提高了数...具有金属 /绝缘层 /半导体 /金属结构的场助热电子发射阴极是大屏幕显示器中的主要候选部件。电子发射受到各层薄膜的厚度、材料组分和结晶状态等的严重影响。由Au/Ag双层薄膜构成的上电极使得电子亲和势降低0 .5 e V,发射电流提高了数倍。半导体材料 Zn1 - x Mgx O具有低的电子亲和势以及适合电子注入的带隙宽度 ,并且已经较为容易地用溅射方法制备。上电极和半导体层之间的晶格匹配可以降低电子在界面上的散射 ,对提高发射电流是很重要的 ,这已经在 Zn1 - x Mgx O/Au和 L i F/Au界面上实现。在绝缘层和半导体层之间引入界面态控制层可以大大降低驱动电压 。展开更多
Two types of secondary emitter materials, the rare earth oxides(RE_2O_3) doped Mo cermet cathodes and the Y_2O_3-W matrix pressed cathode, are introduced in this paper. According to the calculation results, Y_2O_3 exh...Two types of secondary emitter materials, the rare earth oxides(RE_2O_3) doped Mo cermet cathodes and the Y_2O_3-W matrix pressed cathode, are introduced in this paper. According to the calculation results, Y_2O_3 exhibits the best secondary emission property among Y_2O_3,La_2O_3,CeO_2 and Lu_2O_3. The rare earth oxides co-doped Mo cathodes in which Y_2O_3 is the main active substance exhibit better secondary emission property than single RE_2O_3 doped Mo cathode. The results obtained by the Monte-Carlo calculation method show that the secondary electron emission property is strongly related to the grain size of the cathode. The decreasing of the grain size reduces the positive charge effect of the rare earth oxide due to the electrons supplement from the metal to the rare earth oxide, whereby the secondary electrons are easier to escape into the vacuum. Y_2O_3 is introduced into Ba-W cathode to fabricate a pressed Y_2O_3-W matrix dispenser cathode. The result indicates that the secondary emission yield of the Ba-W cathode increases from 2.13 to 3.51 by adding Y_2O_3, and the thermionic emission current density(J_0) could reach 4.18 A/cm^2 at 1050 ℃b.展开更多
Double-walled carbon nanotubes （DWCNTs） with high graphitization have been synthesized by hydrogen arc discharge. The obtained DWCNTs have a narrow distribution of diameters of both the inner and outer tubes, and mo...Double-walled carbon nanotubes （DWCNTs） with high graphitization have been synthesized by hydrogen arc discharge. The obtained DWCNTs have a narrow distribution of diameters of both the inner and outer tubes, and more than half of the DWCNTs have inner diameters in the range 0.6-1.0 nm. Field electron emission from a DWCNT cathode to an anode has been measured, and the emission current density of DWCNTs reached 1 A/cm2 at an applied field of about 4.3 V/~tm. After high-temperature treatment of DWCNTs, long linear carbon chains （C-chains） can be grown inside the ultra-thin DWCNTs to form a novel C-chain@DWCNT nanostructure, showing that these ultra-thin DWCNTs are an appropriate nanocontainer for preparing truly one-dimensional nanostructures with one-atom-diameter.展开更多
Highly adhesive cold cathodes with high field emission performance are fabricated by using a screen-print- ing method. The emission density of carbon nanotube （CNT） cold cathode reaches 207.0 mA cm-2 at an electric ...Highly adhesive cold cathodes with high field emission performance are fabricated by using a screen-print- ing method. The emission density of carbon nanotube （CNT） cold cathode reaches 207.0 mA cm-2 at an electric field of 4.5 Vμm-1 under continuous driving mode, and high peak current emission of 315.8 mA corresponding to 4.5 A cm 2 at the electric field of 10.3 V μm-1 under pulsed driving mode. The emission patterns of the cold cathodes are of excellent uniformity that was revealed by vivid luminescent patterns of phosphor coated transparent indium tin oxide （ITO） an- ode. The cold cathodes also exhibit highly stable emission under continuous and pulsed driving modes. The high adhe- sion of CNTs to molybdenum substrates results in robust cold cathodes and is responsible for the high field emission performance. This robust CNT emitter could meet the operating requirements of continuous and pulsed electron sources, and it provides promising applications in various vacuum- micro/nanoelectronic devices.展开更多
Cathode samples of nano-diamond by graphitization pretreatment with different temperatures were fabricated by electrophoresis, then the structures and morphologies of the cathode samples were characterized by scanning...Cathode samples of nano-diamond by graphitization pretreatment with different temperatures were fabricated by electrophoresis, then the structures and morphologies of the cathode samples were characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD), and the field emission tests were conducted. The effects of graphitization pretreatment on the field emission characteristics of nano-diamond cathode surface on titanium substrate are studied. The results indicate that the surface morphologies of nano-diamond cathode samples after graphitization pretreatment change a lot, and the field emission characteristics in low-voltage area are improved obviously. However, in high-voltage area, the curve distortion happens, and it doesn't conform the mechanism of field emission characteristics.展开更多
文摘具有金属 /绝缘层 /半导体 /金属结构的场助热电子发射阴极是大屏幕显示器中的主要候选部件。电子发射受到各层薄膜的厚度、材料组分和结晶状态等的严重影响。由Au/Ag双层薄膜构成的上电极使得电子亲和势降低0 .5 e V,发射电流提高了数倍。半导体材料 Zn1 - x Mgx O具有低的电子亲和势以及适合电子注入的带隙宽度 ,并且已经较为容易地用溅射方法制备。上电极和半导体层之间的晶格匹配可以降低电子在界面上的散射 ,对提高发射电流是很重要的 ,这已经在 Zn1 - x Mgx O/Au和 L i F/Au界面上实现。在绝缘层和半导体层之间引入界面态控制层可以大大降低驱动电压 。
基金the National Natural Science Foundation of China(GrantNos 51471006,51534009,52621003,51225402)
文摘Two types of secondary emitter materials, the rare earth oxides(RE_2O_3) doped Mo cermet cathodes and the Y_2O_3-W matrix pressed cathode, are introduced in this paper. According to the calculation results, Y_2O_3 exhibits the best secondary emission property among Y_2O_3,La_2O_3,CeO_2 and Lu_2O_3. The rare earth oxides co-doped Mo cathodes in which Y_2O_3 is the main active substance exhibit better secondary emission property than single RE_2O_3 doped Mo cathode. The results obtained by the Monte-Carlo calculation method show that the secondary electron emission property is strongly related to the grain size of the cathode. The decreasing of the grain size reduces the positive charge effect of the rare earth oxide due to the electrons supplement from the metal to the rare earth oxide, whereby the secondary electrons are easier to escape into the vacuum. Y_2O_3 is introduced into Ba-W cathode to fabricate a pressed Y_2O_3-W matrix dispenser cathode. The result indicates that the secondary emission yield of the Ba-W cathode increases from 2.13 to 3.51 by adding Y_2O_3, and the thermionic emission current density(J_0) could reach 4.18 A/cm^2 at 1050 ℃b.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 10974131）, the Nanotechnology Program of Shanghai Science and Technology Committee （No. 0952nm07100）, the Scienceand Technology Innovation Fund of the Shanghai Education Committee （No. 09ZZ85） and Shanghai Pujiang Talent Plan （No. 08PJ1405100）. We thank Professor Shoushan Fan of Tsinghua-Foxconn Nanotechnology Research Center for the HRTEM measurements, and Professor Pingheng Tan of the Institute of Semiconductors for some of the Raman measurements.
文摘Double-walled carbon nanotubes （DWCNTs） with high graphitization have been synthesized by hydrogen arc discharge. The obtained DWCNTs have a narrow distribution of diameters of both the inner and outer tubes, and more than half of the DWCNTs have inner diameters in the range 0.6-1.0 nm. Field electron emission from a DWCNT cathode to an anode has been measured, and the emission current density of DWCNTs reached 1 A/cm2 at an applied field of about 4.3 V/~tm. After high-temperature treatment of DWCNTs, long linear carbon chains （C-chains） can be grown inside the ultra-thin DWCNTs to form a novel C-chain@DWCNT nanostructure, showing that these ultra-thin DWCNTs are an appropriate nanocontainer for preparing truly one-dimensional nanostructures with one-atom-diameter.
基金supported by the National Natural Science Foundation of China(51002161)One-Three-Five Strategic Planning of Chinese Academy of Sciences
文摘Highly adhesive cold cathodes with high field emission performance are fabricated by using a screen-print- ing method. The emission density of carbon nanotube （CNT） cold cathode reaches 207.0 mA cm-2 at an electric field of 4.5 Vμm-1 under continuous driving mode, and high peak current emission of 315.8 mA corresponding to 4.5 A cm 2 at the electric field of 10.3 V μm-1 under pulsed driving mode. The emission patterns of the cold cathodes are of excellent uniformity that was revealed by vivid luminescent patterns of phosphor coated transparent indium tin oxide （ITO） an- ode. The cold cathodes also exhibit highly stable emission under continuous and pulsed driving modes. The high adhe- sion of CNTs to molybdenum substrates results in robust cold cathodes and is responsible for the high field emission performance. This robust CNT emitter could meet the operating requirements of continuous and pulsed electron sources, and it provides promising applications in various vacuum- micro/nanoelectronic devices.
基金supported by the PH.D Start-up Foundation of Yan’an University(No.YD 2010-04)the Special Foundation of Yan’an University(No.YDZD 2011-01)+3 种基金the 2014 Education and Innovation Project of Yan’an University for Graduate Studentthe 2014 Local University National Training Project of Innovation and Entrepreneurship for Undergraduates(No.201410719023)the Special Research Funds for Discipline Construction of High Level University Construction(No.2015SXTS02)the Natural Science Foundation of Shaanxi Province(No.2014JM2-5058)
文摘Cathode samples of nano-diamond by graphitization pretreatment with different temperatures were fabricated by electrophoresis, then the structures and morphologies of the cathode samples were characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD), and the field emission tests were conducted. The effects of graphitization pretreatment on the field emission characteristics of nano-diamond cathode surface on titanium substrate are studied. The results indicate that the surface morphologies of nano-diamond cathode samples after graphitization pretreatment change a lot, and the field emission characteristics in low-voltage area are improved obviously. However, in high-voltage area, the curve distortion happens, and it doesn't conform the mechanism of field emission characteristics.
