Paper NS+AS+EM-MoA3
Enhanced Field Emission from Oxygen-deficient TiO2 Nanotube Arrays
Monday, October 28, 2013, 2:40 pm, Room 203 B
| Session: |
Nanowires and Nanotubes |
| Presenter: |
C.W. Wang, Northwest Normal University, China |
| Authors: |
C.W. Wang, Northwest Normal University, China
J.-B. Chen, Northwest Normal University, China
W.-D. Zhu, Northwest Normal University, China
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| Correspondent: |
Click to Email |
Due to their high aspect ratio, low work function, and excellent controllability of morphology, TiO2 nanotube arrays (TNAs) are found to be promising candidate for field emitters. Further improvement on the field emission (FE) properties of TNAs requires more precise control of both the morphology and the electronic structure. Reduction treatment including hydrogenation, nitriding and carbonization to obtain oxygen-deficient TNAs, is known as a facile strategy to modify the morphology and electronic structure of TNAs [1-3]. In this study, TNAs obtained by anodization are treated by various reduction treatments. It is found that the morphology shows no significant change after hydrogenation at the temperature below 550 °C. But the electronic structure exhibits large variation, which is critically depended on the treatment temperature. When the temperatures of hydrogenation are 400, 450, 500, and 550 °C, the work functions are 3.68, 3.48, 3.03 and 2.20 eV. However, after the treatments of nitriding and carbonization, both the morphology and the electronic structure of TNAs are substantially modified. The nitriding treatment can reconstruct the amorphous TNAs to be nanoworm/nanotube hierarchical structures and implant nitrogen into them, which show lower work function, higher electrical conductivity, and larger field enhancement factor. Correspondingly, after the carbonization treatment, the as-anodized TNAs are successfully transformed to be simetal and a retained tubular morphology with rough surface can be obtained. With respect to FE, compared to as-anodized TNAs, oxygen-deficient TNAs prepared by hydrogenation, nitriding and carbonization show dramatically enhanced FE properties including a lower turn-on field of 1.75 V/µm, a higher FE current density of 4.0 mA/cm2 at 4.50 V/μm, and a remarkable FE stability. These results indicated that oxygen-deficient TNAs can be promising candidates for FE.
Acknowledgements
This work was supported by the National Natural Science Foundation of China (Grant Nos. 10974155 and 10774121), the Natural Science Foundation of Gansu Province of China (Grant No. 1208RJZA197).
References
[1] X. B. Chen, L. Liu, P. Y. Yu and S. S. Mao, Science 2011, 331, 746.
[2] Y. M. Kang, C.W. Wang*, J. B. Chen, L. Q. Wang, D. S. Li, W. D. Zhu and F. Zhou, J. Vac. Sci. Technol. B 2012, 30, 041801.
[3] W. D. Zhu, C. W. Wang*, J. B. Chen, D. S. Li, F. Zhou and H. L. Zhang, Nanotechnology, 2012, 23, 455204.