中国物理B ›› 2014, Vol. 23 ›› Issue (4): 40704-040704.doi: 10.1088/1674-1056/23/4/040704

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A study of transition from n-to p-type based on hexagonal WO3 nanorods sensor

武雅乔, 胡明, 韦晓莹   

  1. School of Electronics and Information Engineering, Tianjin University, Tianjin 300072, China
  • 收稿日期:2013-07-06 修回日期:2013-10-17 出版日期:2014-04-15 发布日期:2014-04-15
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 60771019, 61271070, and 61274074) and the Tianjin Key Research Program of Application Foundation and Advanced Technology, China (Grant No. 11JCZDJC15300).

A study of transition from n-to p-type based on hexagonal WO3 nanorods sensor

Wu Ya-Qiao (武雅乔), Hu Ming (胡明), Wei Xiao-Ying (韦晓莹)   

  1. School of Electronics and Information Engineering, Tianjin University, Tianjin 300072, China
  • Received:2013-07-06 Revised:2013-10-17 Online:2014-04-15 Published:2014-04-15
  • Contact: Hu Ming E-mail:huming@tju.edu.cn
  • About author:07.07.Df; 61.62.Fk; 78.67.Qa
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 60771019, 61271070, and 61274074) and the Tianjin Key Research Program of Application Foundation and Advanced Technology, China (Grant No. 11JCZDJC15300).

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摘要： Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 ℃ using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3 nanorods with diameters ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH=2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range 0.5 ppm-5 ppm and at working temperatures in the range 25 ℃-250 ℃. The obtained WO3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2 gas, the WO3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 ℃, whereas, it behaves as a p-type semiconductor below 50 ℃. The origin of the n-to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 sensors based on hexagonal WO3 nanorods.

关键词: hexagonal, WO3 nanorods sensor, hydrothermal method, n-to p-type transition

Abstract: Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 ℃ using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3 nanorods with diameters ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH=2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range 0.5 ppm-5 ppm and at working temperatures in the range 25 ℃-250 ℃. The obtained WO3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2 gas, the WO3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 ℃, whereas, it behaves as a p-type semiconductor below 50 ℃. The origin of the n-to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 sensors based on hexagonal WO3 nanorods.

Key words: hexagonal, WO3 nanorods sensor, hydrothermal method, n-to p-type transition

中图分类号:  (Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing)

  • 07.07.Df
78.67.Qa (Nanorods)