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Photoelectron Properties of Nanocrystalline TiO 2 Films Prepared by a Powerful Hydrothermal Technique

2012; Wiley; Volume: 95; Issue: 6 Linguagem: Inglês

10.1111/j.1551-2916.2012.05131.x

1551-2916

Caihui Feng, Haifeng Zhang, Yu Wang, Wei Li, Jingran Zhou, Lihua Chen, Lianxiang Yu, Shengping Ruan,

Gas Sensing Nanomaterials and Sensors

In this article, nanocrystalline anatase TiO 2 films were prepared using a powerful hydrothermal technique and characterized by means of X ‐ray diffraction ( XRD ), scanning electron microscope ( SEM ), X ‐ray photoelectron spectroscopic ( XPS ), and UV –vis absorption spectra. A metal–semiconductor–metal ultraviolet ( UV ) detector based on TiO 2 films with Au electrodes was fabricated. The photoelectron properties of the TiO 2 films, including current–voltage ( I–V ) curves under UV illumination, spectral response and response time were studied in detail. The results of the experiment demonstrate that the crystallinity of the TiO 2 film was greatly improved by the hydrothermal technique: the atom ratio between Ti and O on the surface of TiO 2 film is calculated to be 1.87:1, which indicates that the obtained TiO 2 film has less oxygen vacancies. The improved crystallinity as well as the correspondingly decreased hole trap concentrations finally resulted in a short photoresponse decay time of 4.183 s. Meanwhile, a responsivity of 56.5 mA/W, a low dark current of 5.95 nA, a UV photo‐to‐dark current ratio of 10 3 were also obtained for the TiO 2 ‐based detector, all of which suggest that the fabricated TiO 2 films are very promising in UV detection applications.