Xue-Jian Yan

Fudan University, Shanghai, Shanghai Shi, China

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Publications (7)10.28 Total impact

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    ABSTRACT: We report the observation of asymmetric switching dual peaks in ferroelectric copolymer films. These dual peaks occurs when the poling electric field is just below the coercive field and can be removed by continuous application of high enough switching voltage. Our experimental observations can be explained by the injection and the redistribution of space charges in ferroelectric films.
    Chinese journal of chemical physics 09/2010; 23(4):425. DOI:10.1088/1674-0068/23/04/425-430 · 0.72 Impact Factor
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    ABSTRACT: This paper illuminates the preparation of grating-like polystyrene latex monolayer structure, which can minimize the effects of the size deviation of spheres and the defect transfer on the accuracy as calibration samples for microscopes. The latex films are grown on freshly cleaved mica substrates by vertical deposition method. The concentration dependence of the structure and the topography of latex films is characterized by optical microscope, ultraviolet-visible transmission spectrum and scanning probe microscope. The origination of such a grating-like structure is also discussed.
    Chinese Physics B 03/2009; 18(3):997-1001. DOI:10.1088/1674-1056/18/3/025 · 1.39 Impact Factor
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    ABSTRACT: The dependence of polarization fatigue on crystallinity of vinylidene fluoride and trifluoroethylene copolymer films was studied. Experimental data indicated that the higher the crystallinity of the film was, the slower the fatigue rate of the film became. A possible explanation was put forward, and it was regarded that the space charges, trapped at the boundaries of crystallites and/or captured by the defects lying both in amorphous and crystalline phases, should make the major contribution to polarization fatigue.
    Chinese Journal of Polymer Science 01/2009; 27. DOI:10.1142/S025676790900414X · 1.42 Impact Factor
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    ABSTRACT: An AFM image would not be the true topography of a surface because of the limitation of a finite size of the tip. The true topography of the surface can be deduced if we can know the tip shape. In this paper a simple method has been established to determine the profile of an AFM tip. A geometrical model for the tip and a spherical object has been proposed to show the procedure for deducing the tip shape from AFM images. Isolated spheres and closely packed spheres with different diameters have been observed to confirm the tip shape by this method. It is a non-destructive method to determine the tip shape and the results can be used for future reconstruction of an AFM image.
    Ultramicroscopy 05/2008; 108(9):975-80. DOI:10.1016/j.ultramic.2008.04.001 · 2.75 Impact Factor
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    ABSTRACT: An amorphous transparent conductive oxide thin film of molybdenum-doped indium oxide (IMO) was prepared by reactive direct current magnetron sputtering at room temperature. The films formed on glass microscope slides show good electrical and optical properties: the low resistivity of 5.9 × 10− 4 Ω cm, the carrier concentration of 5.2 × 1020 cm− 3, the carrier mobility of 20.2 cm2 V− 1 s− 1, and an average visible transmittance of about 90.1%. The investigation reveals that oxygen content influences greatly the carrier concentration and then the photoelectrical properties of the films. Atomic force microscope evaluation shows that the IMO film with uniform particle size and smooth surface in terms of root mean square of 0.8 nm was obtained.
    Thin Solid Films 04/2006; 500(1-2-500):70-73. DOI:10.1016/j.tsf.2005.11.012 · 1.87 Impact Factor
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    ABSTRACT: The Ag-TCNQ films with smooth surface and uniform tiny grains in nanometer scale were prepared by an improved vacuum evaporation method in which the deposition temperature of TCNQ films was increased from room temperature to 100degC. It is an ideal medium for ultrahigh density data storage with SPM-based techniques. Storage dots were recorded by applying voltage pulses between the tip of a scanning tunneling microscopy (STM) and the substrate under ambient condition. A recording pattern with six storage dots was obtained. The average diameter of recording dots was ~20nm, which corresponds to a data storage density of 0.5 Tbit/cm2
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    ABSTRACT: Molybdenum-doped indium oxide In2O3:Mo (IMO) thin films were deposited on glass substrates by a technique called channel spark ablation. The structure, surface morphology, electrical, and optical properties of these films were investigated by x-ray diffraction, atomic force microscopy (AFM), four-point probe, ultraviolet photoelectron spectroscopy (UPS), Hall analysis, and spectrophotometry. The influence of oxygen pressure on the electrical properties of IMO thin films prepared at Ts=350 °C was studied, showing that increasing oxygen pressure changes the resistivity concavely and the carrier concentration convexly. The IMO films as deposited are well crystallized with a preferred orientation of (222) and the surface roughness evaluated in terms of Rrms, Ra, and Rp-v measured by AFM is 0.72, 0.44, and 15.4 nm, respectively. The lowest resistivity and corresponding carrier concentration are 4.8×10-4 Omega cm and 7.1×1020 cm-3. The typical work function of IMO is 4.6 eV measured by UPS. For all the samples, the average transmittance in the visible region is more than 87%.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 09/2005; 23(5):1350-1353. DOI:10.1116/1.1991871 · 2.14 Impact Factor