Photoelectron Properties of Nanocrystalline TiO₂ Films Prepared by a Powerful Hydrothermal Technique

Abstract

In this article, nanocrystalline anatase TiO2 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 TiO2 films with Au electrodes was fabricated. The photoelectron properties of the TiO2 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 TiO2 film was greatly improved by the hydrothermal technique: the atom ratio between Ti and O on the surface of TiO2 film is calculated to be 1.87:1, which indicates that the obtained TiO2 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 103 were also obtained for the TiO2‐based detector, all of which suggest that the fabricated TiO2 films are very promising in UV detection applications.

Au/TiO2 nanorod‐based Schottky‐type UV photodetectors

“…As it is expected, the photoresponsivity increases from 5.3 to 134.8 A/W as the bias voltage is increased from 1 to 3 V, indicating the generation of more carriers under Au Schottky contact which allows the effective collection of photo-generated free carriers before recombining or trapping. So far, the reported peak responsivities of fabricated UV photodetectors are in the range of 0.1-13 A/W [6,10], which are quite lower than that obtained by us with the Au/TiO 2 (NRs)/FTO device configuration. The enhanced UV photoresponsivity observed in this study could be attributed to hole-traps at the TiO 2 NRs surface incorporated through the adsorbance of O 2 molecules on n-TiO 2 NRs that have a large surface to volume ratio.…”

Ultraviolet detector based on TiO2 nanowire array–polymer hybrids with low dark current

“…Among the UV-sensing materials, TiO 2 (anatase 3.2 eV, rutile 3.0 eV) is believed to be non-toxicity, bio-safe, and possibly biocompatible, which has been used in many applications in our daily life [4,5]. TiO 2 -based UV detectors exhibit superior chemical durability, thermal stability and compact size.…”

Fabrication of flexible ultraviolet photodetectors using an all-spray-coating process

“…[6][7][8] For this reason, photodetectors commonly use materials such as ZnO, SnO 2 , ZnO/CdTe, ZnO/Ti,TiO 2 , GaN, and Ga 2 O 3 . [9][10][11][12][13][14][15] In order to fabricate photodetectors, expensive or complex photolithography and vacuum processes are required, which limits their application and environment for general users. To address this limitation, dispensing methods, such as airbrush spray and the spray pyrolysis process, were introduced to form Ag nanowire and carbon a Authors to whom correspondence should be addressed: shju@kgu.ac.kr 2158-3226/2016/6(4)/045218/7 6, 045218-1 © Author(s) 2016.…”