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The porous anode alumina (PAA) films on silicon substrate with good physicochemical properties have hopeful for the nano-scale devices. The various factors which influence the preparation of high performance PAA film based on silicon were systematically studied, the DC magnetron sputtering technology was used to deposit aluminum and the two-step anodic oxidation method to growth PAA membrane. The results demonstrated that about 2 μm aluminum film deposited on the p-type silicon substrate, in advance deposited 50 nm Ti film on the Si substrate, can get high quality Si-based PAA membrane with good adhesivity, stable structure and consistent pore shape and diameter.

Water-modified ultraviolet (UV) light response of single anodic TiO2 nanotube (NT) is reported in this article. After keeping in deionized water at room temperature, the original smooth surface of amorphous TiO2 NTs is roughened and even changes into sponge-like structure by stacking of further oxidized and crystallized nanodots (NDs) through water-driven surface dissolution process. Two-dimensional variable range hopping (2D-VRH) model is recognized to interpret low-temperature electrical transport properties for the original NT, and the water-modified NT shows deviation from this mechanism owing to the additional electronic tunneling through the surface-crystallized NDs assemblies. The resistance in dark is increased about one order after water-modification due to surface carrier depletion by nanocontacts between crystalline NDs and the original amorphous core. The UV sensitivity S (I-UV/I-dark) of as-prepared single NT is similar to 1.6, and response and recovery times are about 0.39 and 0.45 s, respectively. S is increased to similar to 21.7 after surface water-modification, whereas response and recovery times are increased to 7.1 and 7.5 s, respectively. Surface water-modification will reduce the density of recombination centers and increase the trap state density of carriers in TiO2 NT due to surface charge-separation effect, both leading to the larger UV sensitivity and response time. Single anodic TiO2 NT shows no persistent photocurrent, and it can be applied as high-speed, high-sensitivity UV optoelectronic nanodevices.

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.

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.

In this study, focused gallium ion (Ga+) beam is utilised to fabricate micro/submicron spacing gratings on specimen surface. The grating types include: parallel, cross, and hybrid (grating with double-frequency). Several hybrid gratings with double frequency were produced in combination mode or superposition mode, which have a good potential to measure deformation within different range. Techniques for producing different type of gratings are discussed in detail. As an application, a 5000 lines/mm grating was fabricated on an amorphous SIC MEMS cantilever and was successfully used to measure its virtual strain with aid of digital moiré. The experimental results verify the feasibility of fabricating high frequency grating on metal or non-metal surface using the FIB milling and the resultant grating can be used to measure micro-deformation.

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.

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.

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.

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.

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.

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.

In the work reported in this paper, we have used a low-temperature scanning tunnelling microscope (LT-STM) system to manipulate accurately single atoms. We show how we can use a LT-STM to image and modify a bulk Ag(111) surface and manipulate Ag atoms from substrate and evaporated adsorbates on Ag(111) substrates. We present a synergistic combination of STM-induced modification and ordered arrays of nanometre-scale structures. In particular, we demonstrate the ability to modify Ag atomic nanometre structures on the Ag(111) substrate and some English letters and a Chinese character can be written by single Ag atoms coming from the substrate and evaporated adsorbates on Ag(111). In this way, we supply an effective basis to explore the fundamental physical properties of a nanometre structure and to develop nanotechnology with a `bottom-up' approach.

The response of superconducting Nb films with a diluted triangular and square array of holes to a perpendicular magnetic field are investigated. Due to small edge-to-edge separation of the holes, the patterned films are similar to multi-connected superconducting islands. Two regions in the magnetoresistance R(H) curves can be identified according to the field intervals of the resistance minima. Moreover, in between these two regions, variation of the minima spacing was observed. Our results provide strong evidence of the coexistence of interstitial vortices in the islands and fluxoids in the holes.