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The field emission current variation law of carbon nanotube in a large electric field range (0-32 V m-1) is analyzed in depth by combining the density functional theory with metal electron theory. The results show that their emission current densities are determined by their densities of states, the pseudogap, the length and the local electric field, showing the different variation laws in the different electric field ranges. In the lower electric field (corresponding macroscopic field is less than 18 Vm-1), when their density of states increases, their pseudogap decreases: the two trends are opposite, the former increases the number of electrons for emission, and the latter improves the ability to transfer electrons, they all turn to the increase of the emission current, so their field-emission current density increases linearly with increasing electric field in this range. But in the higher electric field (corresponding macroscopic field is less than 32 Vm-1 and more than 18 Vm-1), their densities of states and the pseudogaps take on the same decrease and increase, so do they in the opposite change case, therefore the emission current density behaves as a non-periodic oscillation in the increasing electric field, moreover the higher electric conductivity lead to the rising of current density, the combined effect of the emitter current density exhibits an oscillatory growth in this electric field range, and the carbon nanotubes behave as ionizing radiation. So the too high electric field may cause the emission current to be instable. The electric conductivity variation law of the metallic carbon nanotube is further studied in this paper. In the lower electric field (corresponding macroscopic field is less than 5 Vm-1), the electric conductivity of CNT increases linearly with increasing electric field; when the macroscopic electric field increases up to a value in a range from 5 to 14 Vm-1, the electric conductivity only changes like a slight concussion in (6.3-9.9)1017Sm-1 range, when the macroscopic electric field increases to a value in a range from 16 to 32 Vm-1, the electric conductivity appears as a sharp oscillation growth trend. Additionally, the specific binding energy of CNT is enhanced with increasing electric field, accordingly the structural stability turns better and the cone-capped carbon nanotubes could be used for emission cathode material. The calculation results are consistent with the experimental results of the literature.
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Keywords:
- carbon nanotubes /
- field emission /
- current density /
- electric conductivity
[1] Heer W A D, Chatelain A, Ugarte D 1995 Science 270 1179
[2] Meyyappan M (translated by Liu Z F) 2005 Carbon Nanotubes: Science and Applications (Beijing: Science Press) pp223-228 (in Chinese) [M. 麦亚潘主 著 (刘忠范 译) 2007 碳纳米管科学与应用 (北京: 科学出版社) 第233228页]
[3] Li X, Zhou W M, Liu W H, Wang X L 2015 Chin. Phys. B 24 057102
[4] Xie Y, Zhang J M 2011 Chin. Phys. B 20 127302
[5] Zhang X, Song Y R 2014 Chin. Phys. B 23 064204
[6] Fowler R H, Nordheim L 1928 Proc. R. Soc. A 119 173
[7] Uh H S, Park S S 2015 Diamond and Related Materials 54 74
[8] Modinos A 1984 Field, Thermionic, and Secondary Electron Emission Spectroscopy (Plenum Publishing Corp) pp36-37
[9] Jiang J, Feng T, Cheng X H 2006 Mater. Lett. 60 1085
[10] Liu X H, Zhu C C, Li Y K 2004 Physics B 344 243
[11] Hartschuh A 2003 Science 301 1354
[12] Qu C Q, Qiao L, Wang C, Yu S S, Zheng W T, Jiang Q 2010 Phys. Lett. A 374 782
[13] Yao Z, Kane C L, Dekker C 2000 Phys. Rev. Lett. 84 2941
[14] Cui Y T, Zhang X B, Lei W 2013 High Power Laser And Particle Beams 25 1509 (in Chinese) [崔云涛, 张晓兵, 雷威 2013 强激光与粒子束 25 1509]
[15] Delley B J 1990 Chem. Phys. 92 508
[16] Wang X Q, Li L, Zhu N J 2008 Acta Phys. Sin. 57 7173(in Chinese) [王新庆, 李良, 褚宁杰 2008 物理学报 57 7173]
[17] Jo S H, Wang D Z, Huang J Y 2004 Appl. Phys. Lett. 85 810
[18] Ma H L, Huo H B, Zeng F G 2013 Acta Phys. Sin. 62 158801(in Chinese) [麻华丽, 霍海波, 曾凡光 2013 物理学报 62 158801]
[19] Chen C L 2007 Solid-State Physics (Beijing: Science Press) pp167-168 (in Chinese) [陈长乐 2007 固体物理 (北京: 科学出版社) 第167168页]
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[1] Heer W A D, Chatelain A, Ugarte D 1995 Science 270 1179
[2] Meyyappan M (translated by Liu Z F) 2005 Carbon Nanotubes: Science and Applications (Beijing: Science Press) pp223-228 (in Chinese) [M. 麦亚潘主 著 (刘忠范 译) 2007 碳纳米管科学与应用 (北京: 科学出版社) 第233228页]
[3] Li X, Zhou W M, Liu W H, Wang X L 2015 Chin. Phys. B 24 057102
[4] Xie Y, Zhang J M 2011 Chin. Phys. B 20 127302
[5] Zhang X, Song Y R 2014 Chin. Phys. B 23 064204
[6] Fowler R H, Nordheim L 1928 Proc. R. Soc. A 119 173
[7] Uh H S, Park S S 2015 Diamond and Related Materials 54 74
[8] Modinos A 1984 Field, Thermionic, and Secondary Electron Emission Spectroscopy (Plenum Publishing Corp) pp36-37
[9] Jiang J, Feng T, Cheng X H 2006 Mater. Lett. 60 1085
[10] Liu X H, Zhu C C, Li Y K 2004 Physics B 344 243
[11] Hartschuh A 2003 Science 301 1354
[12] Qu C Q, Qiao L, Wang C, Yu S S, Zheng W T, Jiang Q 2010 Phys. Lett. A 374 782
[13] Yao Z, Kane C L, Dekker C 2000 Phys. Rev. Lett. 84 2941
[14] Cui Y T, Zhang X B, Lei W 2013 High Power Laser And Particle Beams 25 1509 (in Chinese) [崔云涛, 张晓兵, 雷威 2013 强激光与粒子束 25 1509]
[15] Delley B J 1990 Chem. Phys. 92 508
[16] Wang X Q, Li L, Zhu N J 2008 Acta Phys. Sin. 57 7173(in Chinese) [王新庆, 李良, 褚宁杰 2008 物理学报 57 7173]
[17] Jo S H, Wang D Z, Huang J Y 2004 Appl. Phys. Lett. 85 810
[18] Ma H L, Huo H B, Zeng F G 2013 Acta Phys. Sin. 62 158801(in Chinese) [麻华丽, 霍海波, 曾凡光 2013 物理学报 62 158801]
[19] Chen C L 2007 Solid-State Physics (Beijing: Science Press) pp167-168 (in Chinese) [陈长乐 2007 固体物理 (北京: 科学出版社) 第167168页]
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