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Nanotechnology characterization, surface characterization, thin film characterization, semiconductor characterization, material characterization, nanoparticle characterization free downloads papers articles reports
Abstract:
"Characterization Methods for Nanotechnology"
Satyadhar Joshi
Indore Satyadhar_joshi@yahoo.com
Materials characterization at increasingly small dimensions is a critical part of many manufacturing industries, including semiconductors, optoelectronics, automotive and aerospace. All of these industries are increasingly using small scales and more tightly controlled processes as part of the traditional evolution of manufacturing towards smaller, lighter, faster or stronger characteristics, depending on the application. On top of the evolutionary aspect of dimensional shrinkage is the use of 'new' materials or 'new' processes that may carry their own novel properties or design issues not previously encountered.
Growth in the micro- and Nano- engineering industry has led to increased demand for analytical and characterization methods for these materials and systems. We know that Nano-products with high surface area-to-volume ratios are more sensitive to impurities and micro contamination during processing than larger geometry products, resulting in defects and yield loss in production.
This project demonstrates contributions that surface analytical methods can make towards problem solving during the manufacture and reliability characterization of new materials. These techniques include: SEM (Scanning Electron Microscope), TEM (Transmission Electron Microscope), XPS (X-ray Photoelectron Spectroscopy) and XRD (X-ray Diffraction). Examples of these techniques as characterization tools in the Nano-dimension will be given, with a discussion of their relative strengths and weaknesses.
The focus in this project is on the different types of scanning probe microscope, their applications in nanotechnology and comparison of different type of microscopy. Characterization of Carbon Nanotubes and other important Nano materials and thin films with different type of techniques and their advantages and disadvantages.
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Scanning probe microscopy (SPM) is a new branch of microscopy that forms images of surfaces using a physical probe that scans the specimen. An image of the surface is obtained by mechanically moving the probe in a raster scan of the specimen, line by line, and recording the probe-surface interaction as a function of position. was founded with the invention of the scanning tunneling microscope in 1981.
scanning tunneling microscope
The scanning tunneling microscope (STM) is a non-optical microscope that scans an electrical probe over a surface to be imaged to detect a weak electric current flowing between the tip and the surface.
The STM allows scientists to visualize regions of high electron density and hence infer the position of individual atoms and molecules on the surface of a lattice.
The STM is capable of higher resolution than its somewhat newer cousin, the atomic force microscope (AFM). Both the STM and the AFM fall under the class of scanning probe microscopes.
The STM can obtain images of conductive surfaces at an atomic scale 0.2 nanometer, and also can be used to manipulate individual atoms, trigger chemical reactions, or reversibly produce ions by removing or adding individual electrons from atoms or molecules.
The STM is a non-optical microscopy technique which employs principles of quantum mechanics. A sharp probe (the tip), whose end is as sharp as a single atom, moves over the surface of the material under study, and a voltage is applied between the probe and the sample surface. Depending on the voltage applied, electrons will tunnel through the potential barrier between the surface and probe, resulting in a weak electric current. The direction of the tunneling depends on the polarity of the electric field. The magnitude of this current is exponentially dependent on the distance between probe and the surface. For tunneling to occur, the substance being scanned must be conductive (or semiconductive). Insulators cannot be scanned by STM, as the electron has no available energy state to tunnel into or out of due to the band gap structure in insulators.
The scanning electron microscope (SEM) is a type of electron microscope capable of producing high-resolution images of a sample surface. Due to the manner in which the image is created, SEM images have a characteristic three-dimensional appearance and are useful for judging the surface structure of the sample.
The scanning electron microscope (SEM) is one of the most versatile instruments
available for the examination and analysis of the microstructure morphology and
chemical composition characterizations. It is necessary to know the basic princi-
ples of light optics in order to understand the fundamentals of electron microscopy.
The unaided eye can discriminate objects subtending about 1/60° visual angle, cor-
responding to a resolution of ~0.1 mm (at the optimum viewing distance of
25 cm). Optical microscopy has the limit of resolution of ~2,000 Å by enlarging
the visual angle through optical lens. Light microscopy has been, and continues to
be, of great importance to scientific research.
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