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Li J.,Fujian University of Technology | Li J.,Fuzhou University | Chen W.,Fujian University of Technology | Chen W.,Fuzhou University | And 8 more authors.
Journal of Physics and Chemistry of Solids | Year: 2014

Ag-doping TiO2 composite nanotubes (Ag-TNTs) were synthesized by alkaline fusion followed by hydrothermal treatment. The microstructure and morphology of the materials were characterized by XRD, TEM, XPS, SPS (surface photovoltage spectroscopy), FISPS (electric field-induced surface photovoltage spectroscopy) and Raman spectroscopy. First-principles calculations based on density-functional theory (DFT) showed the formation of several impurity levels near the top of the valence band in the band gap (Eg) of rutile TiO2 due to Ag doping. A "double junction" is proposed, involving a Schottky junction and p-n junction (denoted as "Ag-p-n junction") occurring between the Ag particles and the nanotube surface, as well as forming inside TiO2 nanotubes, respectively. The strongly built-in electric field of the junctions promotes the separation of photo-holes and photoelectrons, enhancing the photocatalytic efficiency. XRD results indicated that the composite Ag-TNTs exist as a mixture of anatase and rutile phases. XPS results showed that Ti4+ is the primary state of Ti. Raman spectral analysis of Ag-TNTs revealed the presence of a new peak at 271 cm-1. The red-shift of the absorption light wavelength of Ag-TNTs was 0.16 eV (20 nm) due to a considerable narrowing of Eg by the existing impurity levels. © 2013 Elsevier Ltd. Source


Lin W.,Fuzhou University | Lin W.,Fujian Key Laboratory of Microelectronics and Integrated Circuits | Huang S.-Z.,Fuzhou University | Huang S.-Z.,Fujian Key Laboratory of Microelectronics and Integrated Circuits | Chen W.-Z.,Fuzhou University
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2010

The SnO2/WO3 double layer thin film was prepared by magnetron sputtering in which a tin (Sn) target and a tungsten (W) target were operated in radio frequency (RF) reactive mode. The crystallographic structure of the composite was investigated by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy (XPS). Results reveals that the SnWO4 is formed by SnO2 and WO3. The sensor using the SnO2/WO3 double layer thin film was prepared, the preparation technology parameter, operated condition and the gas-sensing properties of the SnO2/WO3 double layer thin film sensor, such as sensitivity, selectivity, response and recovery, were researched. The results indicate that the sensor has the good sensitivity to NO2 gas, and is insensitive to other disturbance gases. Source


Wei L.,Fuzhou University | Wei L.,Fujian Key Laboratory of Microelectronics and Integrated Circuits | Shizhen H.,Fuzhou University | Shizhen H.,Fujian Key Laboratory of Microelectronics and Integrated Circuits | Wenzhe C.,Fuzhou University
Advanced Materials Research | Year: 2010

A novel nanocomposite thin film material of SnO2/WO3 metal oxide compound doped by multi-walled carbon nanotubes (MWCNT) and its corresponding gas sensor were prepared by radio frequency (RF) reactive magnetron sputtering. The surface composition and chemical elements of the thin film material were respectively analyzed and validated by X-ray diffraction (XRD) and photoelectron spectroscopy (XPS). The influencing factors of gas sensing properties were studied and the test results of gas sensor were analyzed. The results indicated that the detection using the composite material gas sensors for low concentration NO2 toxic gas could be greatly improved by MWCNTs which were doped on the mixed oxides matrix. A possible mechanism explaining the behaviour of the thin film gas sensor was introduced. © (2010) Trans Tech Publications. Source


Wei L.,Fuzhou University | Wei L.,Fujian Key Laboratory of Microelectronics and Integrated Circuits | Shizhen H.,Fuzhou University | Shizhen H.,Fujian Key Laboratory of Microelectronics and Integrated Circuits | Wenzhe C.,Fuzhou University
Journal of Semiconductors | Year: 2010

An MWCNT-doped (multi-walled carbon nanotube) SnO2 thin film NO2 gas sensor, prepared by radio frequency reactive magnetron sputtering, showed a high sensitivity to ultra-low concentrations of NO 2 in the parts per billion range. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy (SEM) characterizations indicated that the MWCNTs were affected by the morphology of the SnO2 thin film and the particle size. The properties of the MWCNT-doped SnO2 sensor, such as sensitivity, selectivity, and response-recovery time, were investigated. Experimental results revealed that the MWCNT-doped SnO2 thin film sensor response to NO2 gas depended on the operating temperature, NO2 gas concentration, thermal treatment conditions, film thickness, and so on. The mechanism of the gas-sensing property of the MWCNT-doped Sn22 thin film sensor was investigated and showed that the improved gas-sensing performance should be attributed to the effects between MWCNTs (p-type) and SnO2 (n-type) semiconductors. © 2010 Chinese Institute of Electronics. Source


Lin W.,Fuzhou University | Lin W.,Fujian Key Laboratory of Microelectronics and Integrated Circuits | Huang S.-Z.,Fuzhou University | Huang S.-Z.,Fujian Key Laboratory of Microelectronics and Integrated Circuits | And 2 more authors.
Information Technology Journal | Year: 2013

As circuit sizes grow ever larger, test data volume and test application time grow unwieldy even in the very efficient scan based designs. Adaptive scan architecture of Design for Test (DFT) technique is used to reduce test application time and test data volume. In our research, we analyze the technique of the scan test architecture. Based on the analysis, the adaptive scan of DFT technique is succeeding applied to a SOC chip. Experimental results show that the test cost of the SOC chip is greatly reduced. Compared with the original program, the fault coverage is reached 97%, the test data volume is decreased 8.79 times, the test time is reduced almost 6 times. © 2013 Asian Network for Scientific Information. Source

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