Papers by Keyword: Atomic Force Microscope (AFM)

Abstract: Objective: The aim of study is to investigate the composite resins superficial roughness and microstructure after brushing with common dentifrices containing silica abrasive agent or bicarbonate and whitening dentifrices containing peroxide. Methods: Roughness measuring instruments were used to test 3M Filtek Z350 samples surface brushed by the silica abrasive (C), urea peroxide + alumina / silica (RP), the hydrogen peroxide + calcium carbonate (Ex) dentifrices before and after, using AFM to observe the superficial properties. Results: The superficial roughness after using the three dentifrices changed differently, followed by EX<RPConclusions: Relative to dentifrices containing silica abrasive, whitening dentifrices containing peroxide and alumina or silica or calcium carbonate composition has smaller friction resistance of the composite resins.

Abstract: The migration of a recrystallization boundary in pure aluminum was followed during in situ annealing in a scanning electron microscope. The microstructure was characterized using the electron channeling contrast technique and a typical stop-go grain boundary motion was observed during annealing. The thermal grooving associated with boundary migration on the inspected free surface was characterized after the in-situ experiment using atomic force microscopy. The results show that new thermal grooves develop at places where the recrystallization boundary segments remain stationary for a relatively long time. The kinetics of thermal grooving are determined and effects hereof on the boundary migration are discussed.

Abstract: Nanocrystalline titanium dioxide (TiO2) thin films have been prepared by dip coating method. The TiO2 thin films have been coated on glass substrate and annealed at 400, 450 and 500° C respectively. The X- ray diffraction pattern shows that TiO2 nanocrystalline thin films are of anatase structure and the grain size is found to be in the range of 20-35 nm. The annealed films have been observed to be nanocrystalline in nature and the crystallinity has been observed to improve on annealing. The surface topography of the films has been studied using atomic force microscope. The optical properties have been studied using transmittance spectra. The band gap has been found to lie in the range of 3.70 to 3.83 eV depending on the annealing temperature.

Abstract: Using the microwave atomic force microscope (M-AFM) measuring system, the sample of Au nanowires arranged on glass wafer was sensed with three kinds of scanning speed. As the results shown, the spatial resolution of topographies is increased with the decrease of scanning speed. However, the precision of microwave images is not changed much with decreasing the scanning speed. Since M-AFM with the compact microwave instrument can always implement the real time measurement, the variation of scanning speed will not affect the microwave measurement.

Abstract: In this work, we have investigated the fabrication of Double gate and Single gate Junctionless silicon nanowire transistor using silicon nanowire patterned on lightly doped (10⁵ cm^-3) p-type Silicon on insulator wafer fabricated by Atomic force microscopy nanolithography technique. Local anodic oxidation followed by two wet etching steps, Potassium hydroxide etching for Silicon removal and Hydrofluoric acid etching for oxide removal, were implemented to reach the structures. Writing speed and applied tip voltage were held in 0.6 µm/s and 8 volt respectively for Cr/Pt tip. Scan speed was held in 1.0 µm/s. The etching processes were elaborately performed and optimized by 30%wt. Potassium hydroxide + 10%vol. Isopropyl alcohol in appropriate time, temperature and humidity. The structure is a gated resistor turned off based on a pinch-off effect principle, when essential positive gate voltage is applied. Negative gate voltage was unable to make significant effect on drain current to drive the device into accumulation mode.

Abstract: Objective: To investigate the microstructures and mechanical characteristics of enamel and dentin of primary and permanent teeth by AFM, analyze their relationships and provide information for bionics and designs of dental materials. Methods: After embedding, cutting and grinding, 10 primary teeth and 10 permanent teeth were randomly divided into four groups. The morphology of samples was obtained by AFM and the roughness and Young’s modulus were calculated by JPK DP Data processing version 4.0 software. Results: In permanent teeth groups, the enamel rods arrange more tightly than those in primary teeth groups. The roughness of primary enamel （1203±39.5nm）was higher than permanent teeth（954.6±30.5nm）.The Young′s modulus of enamel in primary teeth（80.4±7.7GPa）was lower than permanent teeth（90.8±2.2GPa）. The roughness of dentin in primary teeth （1695±67.6nm）is higher than permanent teeth （1210±45.3nm）and the Young′s modulus of dentin in primary teeth（19.8±1.9 GPa）was lower than the permanent teeth （23.1±1.0 GPa）. Conclusions: The mechanical characteristics of primary and permanent teeth are closely related to their microstructures.

Abstract: Tantalum nanoparticle (NP) films have been deposited on silicon substrates, using sputter deposition with gas aggregation. The resultant NP films have been characterized using high resolution atomic force microscopy and X-ray fluorescence spectroscopy. The films remain stable and the NPs maintain a spherical structure on annealing up to 600 °C. In addition to characterization, these NP films have been locally patterned by atomic force microscope scanning of the surface in contact mode.

Abstract: Use Atomic Force Microscope to analyze surface morphology of the laboratory prepared Mg-doped zinc oxide films and standard gratings. Main measuring method is the use of semi-contact mode of the Atomic Force Microscope (tapping mode). When parameters such as frequencies and gains do not change, we focus on the differences of the results under different feedback speed (FB) working on the specimens, and sum up the relations between the feedback speed (FB) and the definition of the surface morphology of the specimens.

Abstract: We present the study of the growth of ZnO nanorods on p-Si (100) using MBE. Various characterization techniques such as Fourier transform infra-red (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy and capacitance – voltage (C-V) measurements were employed to analyze and assess the grown ZnO nanorods. AFM clearly demonstrated the growth of vertically aligned nanorods, however, they get diffused as the thickness of the layer is increased beyond 1 µm. C-V measurements in particular, justified p-n junction between Si/ZnO nanorods. The junction showed n-type conductivity with carrier concentration 1×10¹⁵ cm^-3. The source of this n-type conductivity was Zn-interstitials and the presence of Zn-interstitials was confirmed by EDAX and Raman spectroscopy. Experimental detail and results were presented that help in furtherance of our understanding of the material issues and its potential as required for the practical devices.

Abstract: Aluminium (Al) thin films on polyimide (PI) plastic substrates prepared via thermal evaporation technique and annealed in nitrogen (N₂) ambient at different temperatures (250 - 400°C, for 30 minutes) have been investigated. Structural properties of the as-evaporated film have been studied by high resolution X-ray diffraction (HR-XRD). The result illustrates crystalline nature of the Al thin film with a dominant Al (111) peak at 2θ = 38.4°. Atomic force microscope (AFM) shows increased surface roughness root mean square (RMS) with increased annealing temperature (with roughness of 11.96 nm at 400°C). Sheet resistance drops with increased temperature and records the lowest reading (64 mΩ/) at 400°C. Besides, increased annealing temperature also results in reduced surface reflectance (with minimum reflectance of 73% reflectance in the visible region at 400°C). The effects of the resulting Al back contact properties towards thin film silicon (Si) solar cells on PI substrates were subsequently discussed.