Papers by Author: Chang Zhi Gu

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Authors: Kai Ge Wang, Peng Ye Wang, Shuang Lin Yue, Ai Zi Jin, Chang Zhi Gu, Han Ben Niu
Abstract: In the emerging field of nanobiotechnology, further downsizing the fluidic channels and pores to the nanometer scale are attractive for both fundamental studies and technical applications. The insulation Silicon nitride membrane nanofluidic channel arrays which have width ~50nm and depth ~80nm and length ≥20μm were created by focused-ion-beam instrument. The λ-DNA molecules were put inside nanochannels and transferred, a fluorescence microscopy was used to observe the images. Only by capillary force, λ-DNA molecules moved inside the nanochannels which dealt with activating reagent Brij aqueous solution. These scope nanostructure devices will help us study DNA transporting through a nanopore and understand more DNA dynamics characteristics.
Authors: C.Y. Shi, Qi Wang, Shuang Lin Yue, Chang Zhi Gu
Abstract: Nanoscaled silicon cone arrays were formed on mirror-polished silicon wafers by plasma etching using hot filament chemical vapor deposition (HFCVD) system. A mixture of CH4 and H2 was introduced during silicon cone formation. AlN films were coated on Si cone arrays using radio frequency (RF) magnetron sputtering system. Scanning electrons microscopy (SEM) was employed to characterize the morphology of silicon cone arrays before and after AlN coating. The field emission characteristics of AlN coated silicon cone arrays,uncoated silicon cone arrays and AlN films were studied and compared, and the silicon cone arrays with AlN coating showed the best enhanced electron emission properties due to the negative electron affinity of AlN coating layer and the high aspect ratio of silicon cone. For AlN coated silicon cone arrays, a slight hysteresis between the upward and downward voltage sweeps was also observed and the field emission currents from AlN coated Si nanocone arrays decreased with the increase of the thickness of AlN films, which could be mainly attributed to the space charge buildup in AlN film with wide band gap.
Authors: Bin Sun, Hong Xing Yin, Meng Meng Li, Yun Ze Long, Chang Zhi Gu
Abstract: In this paper, we report on fabrication and physical properties of carbon microcoils, which are prepared by a chemical vapor deposition (CVD) process with Ni-catalyzed pyrolysis of acetylene, and characterized by a scanning electron microscope, a transmission electron microscope and an infrared spectrometer. The dark electrical conductivity of an isolated carbon microcoil is about 81 S/cm at room temperature, and its temperature dependence follows three-dimensional Mott variable-range hopping (VRH) model. Particularly, evident photocurrent is observed in the carbon microcoil upon cameral flash illumination. In addition, it is found that the surface of microcoil film is hydrophobic, showing a large water contact angle of about 135°. These results indicate that carbon microcoils have excellent physical properties, and can be used as optoelectronic and reinforced materials.
Authors: Hua Du, Hui Min Xie, Hai Chang Jiang, Li Jian Rong, Qi Ang Luo, Chang Zhi Gu, Ya-Pu Zhao
Abstract: In this paper, a new technique for fabricating grating on the surface of porous TiNi SMA is proposed. The grating is directly written onto the surface of the specimen using the FIB milling. No photoresist is required during the lithography process. From the experimental results, it can be obviously seen that the grating fabricated by FIB milling has a better quality than that by electron beam lithography. Using the self-made FIB grating, the in-plane deformation of the porous TiNi SMA in microscale is studied by SEM moiré method. Moiré and the microscopical structures are synchronously observed, including microcracks, martensites and grain boundaries.
Authors: P. Xu, J.J. Li, Chang Zhi Gu
Abstract: Titanium containing carbon nitride (CNx) films are prepared by radio frequency magnetron sputtering method. The evolution of intrinsic stress within the nanocomposite films is monitored during growth by using an in situ bending-plate method. The effect of Ti-containing concentration on intrinsic stress is investigated. XRD data shows that TiN nanocrystals are synthesized to embed into the CNx matrix. The film intrinsic stress depends obviously on the content of Ti. We suggest that grain boundary effect is responsible to the intrinsic stress variation as a function of the content of Ti.
Authors: Cheng Chun Tang, Rong Huang, Yun Ze Long, Bin Sun, Hong Di Zhang, Chang Zhi Gu, Wen Xiu Wang, Jun Jie Li
Abstract: Polyaniline (PANI) is a promising functional polymer in the field of toxic gas detection. In this paper, nano-branched coaxial PANI fibers were grown on electrospun poly(methyl methacrylate) (PMMA) nanofibers by an in situ chemical oxidative polymerization method. The resultant PANI/PMMA fibers were characterized by scanning electronic microscopy and Raman spectrum analysis. The conductivity of an individual coaxial PANI/PMMA fiber is about 2.123 S/cm and that of the conducting PANI coating layer is about 21.8 S/cm. The ammonia sensing properties of the samples were tested by means of impedance analysis. The nano-branched PANI fibers can response significantly to low concentration of ammonia due to large specific surface area, and the sensitivity shows good linear relationship to the ammonia concentration of ppm level. These results indicate that nano-branched coaxial PANI fibers are promising candidate for detection of toxic ammonia gas.
Authors: Shuang Lin Yue, C.Y. Zhi, Chang Zhi Gu
Abstract: By using radio frequency magnetron reactive sputtering system, (002)-oriented AlN film was deposited on W tip. The field emission from (002)-oriented AlN film on W tip was studied and compared with that from the bare W tip in a high vacuum (≤10-6 Pa) chamber. It indicated that the enhanced electron emission could be obtained from the (002)-oriented AlN film on W tip. The corresponding Fowler-Nordheim plot of AlN presented a nonlinear behavior in nature related the high resistivity of AlN. Furthermore, the current-electric field (I-E) curve presented excellent reproducibility checked by repeated measurements.
Authors: Chang Zhi Gu, Ai Zi Jin, Z.L. Wang, J.J. Li
Abstract: Sub-micrometer diamond tube arrays are formed on freestanding diamond film via focused ion beam pattern technology and chemical etching method. First, the sub-micrometer holes are fabricated on Si substrate by using FIB milling method. Then, diamond film is grown by hot filament chemical vapor deposition method on patterned Si substrate. By controlling the deposition parameters, the diamond can be grown along the wall of holes and the diamond tubes in sub-micrometer scale are formed. Finally, Si substrate is etched by chemical etching method and the diamond tube arrays are fabricated on a freestanding diamond film. Scanning electron microscopy and Micro-Raman spectroscopy measurements are performed to characterize the structure and phase purity of diamond tubes. The electron emission properties from the diamond tube arrays are studied, the result presents that the enhanced emission property can be obtained from diamond tube arrays.
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