Advanced Materials Characterization Workshop 2009

2009 AMC Workshop Program

Abstracts: Tutorials

"Materials characterization: The need for complementary techniques"

     Prof. Ivan Petrov, Frederick Seitz - Materials Research Laboratory.

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"Atomic force microscopy"

     Dr. Scott MacLaren, Frederick Seitz - Materials Research Laboratory.

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"X-ray diffraction, reflectometry and fluorescence"

     Dr. Mauro Sardela, Frederick Seitz - Materials Research Laboratory.

Practical aspects of data acquisition and interpretation using x-ray diffraction, reflectivity and fluorescence will be discussed. Overview of basic diffraction principles, reciprocal space and instrument operation modes will be presented. Cases studies of materials characterization in various fields will be used to present x-ray based analytical methods employed in the determination of phases and crystallographic structure, grain sizes, strain, preferred orientation, residual stress, layer thickness, interface roughness, composition and mosaicity. Examples will range from powder diffraction analysis to thin film characterization and high-resolution reciprocal space mapping. Potential artifacts during measurement and data interpretation will also be discussed in addition to cross-comparison of data acquired by other complementary techniques

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"Optical characterization of materials"

     Dr. Julio Soares, Frederick Seitz - Materials Research Laboratory.

In this tutorial, we will give an overview of the physical principles behind light interaction with matter. Several different techniques to measure, and manipulate light used for different characterization techniques will be presented. Examples of application of the several techniques for material characterization, and complementary analysis strategies will be discussed.

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"Auger electron spectroscopy and X-ray photoelectron spectroscopy"

     Dr. Richard Haasch, Frederick Seitz - Materials Research Laboratory.

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"Rutherford backscattering and secondary ion mass spectrometry"

     Dr. Timothy Spila, Frederick Seitz - Materials Research Laboratory.

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"Scanning Electron Microscopy and Focused Ion Beams in Materials Research"

     Dr. Wacek Swiech, Jim Mabon, Vania Petrova, Mike Marshall, and Ivan Petrov, Frederick Seitz - Materials Research Laboratory.

Scanning Electron Microscopy (SEM) is a technique that offers various methods of imaging and analyzing the surface of bulk materials. It offers much higher lateral resolution and higher depth of focus than optical microscopies. The SEM is the most widely-used type of electron microscope and often requires little or no sample preparation. SEM images are formed by scanning the sample surface with a beam of electrons in a raster scan pattern. The electrons interact with the atoms that make up the sample producing signals that contain information about the sample's surface topography, composition and other properties. These signals include secondary electrons, backscattered electrons, X-rays, and electron currents. Analytical modes of operation include X-ray Energy Dispersive Spectroscopy (X-EDS), Wavelength Dispersive X-ray Spectroscopy (WDS), Electron Backscattered Diffraction (EBSD), Electron Beam Induced Current (EBIC), Cathodoluminescence (CL) and others. EDS and WDS are analytical techniques used for the elemental analysis or chemical characterization of a sample at the sub-micron scale. Measurements of crystallographic orientation, micro-texture mapping, and phase identification are available by acquisition of EBSD patterns. The focus of the presentation is on the description of the techniques’ details, capabilities and advantages. Some fundamentals of Focused Ion Beam (FIB) technique and its applications will be additionally presented.

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"Transmission electron microscopy"

     Dr. Jianguo Wen, Frederick Seitz - Materials Research Laboratory.

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Abstracts: Application highlights

"Thin film characterization with spectroscopic ellipsometry"

     Dr. Andrea Fuchser, J.A.Woollam.

Spectroscopic Ellipsometry (SE) is a powerful optical measurement used to study thin film properties. It can provide accurate and precise characterization of thin film thickness and optical constants (n and k). Additional material properties, such as optical anisotropy, surface roughness, optical gradients, doping concentration, and material composition can also be studied. The flexibility of SE has opened up applications in very diverse areas; including semiconductor, photolithography, photovoltaic, optical coating, biochemistry, displays, and more.

We will provide a quick introduction to fundamental theory, SE measurements, and demonstrate common applications. We will also review a few exciting new research areas where SE is being applied; including nanostructures, metamaterials, photovoltaics, organic electronics, and more.

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"XRD and AFM - One plus one is three"

     Dr. David Sampson and Heiko Ress, Bruker AXS Inc.

Bruker AXS develops advanced analytical system for material research using X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD analysis determines crucial sample parameters including layer thickness, roughness, composition, strain and bowing. Using X-ray microdiffraction and 2-dimensional detectors very small sample amounts or spots can be analyzed. Bruker AFM combine an optical microscope with research-quality AFM. The interferometric detection system provides advanced modes such as electrostatic force microscopy, spreading resistance, surface potential and scanning capacitance. The advance imaging techniques take AFM's beyond standard topography.
While AFM and XRD give more or less complimentary material information, the combination of both methods can provide real understanding of new materials and accelerate their functional improvement.
This talk will concentrate on practical examples from semiconductors, solar cells and new nanomaterials.

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"Structural characterization of nanocrystalline and amorphous materials using high-energy X-ray diffraction on a laboratory system"

     Dr. Milen Gateshki, Hans te Nijenhuis, Detlef Beckers, and Martijn J Fransen, PANalytical B. V.

Recent interest in the understanding of physical and chemical properties of nanomaterials has increased the need to analyze structures on a local (nano) scale. However, the atomic structures of nanocrystalline and amorphous substances are not accessible by conventional methods used to study crystalline materials due to the short-range ordering present in these materials. One of the most promising techniques to study nanostructures is by using total scattering X-ray diffraction experiments combined with the pair distribution function (PDF) analysis.
The pair distribution function provides information about the probability of finding atoms separated at a certain distance. This technique require X-ray radiation with high photon energy and flux intensity usually associated with synchrotron facilities.
In this presentation we will discuss the possibilities for PDF analysis on a standard laboratory system using a tube with silver anode as a source of X-rays source. The characteristic Ag Kα radiation has energy of 22 keV corresponding to a wavelength is 0.05564 nm.
Different samples including crystalline, nanocrystalline, amorphous solids and liquids with known structures have been used to test the applicability of the data collected with a laboratory diffractometer for PDF analysis. Meaningful results have been achieved, even though the X-ray photon energies are not as high as those attainable with synchrotron radiation. The method has been successfully applied also to geopolymers - amorphous materials with application in building materials and for the investigation of the crystallization processes in lactose.

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"Organic Thin Film Analysis with XPS"

     Dr. Kenneth D. Bomben, Physical Electronics.

The analysis of multi-layer inorganic films using ion sputtering combined with the surface analysis techniques of Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS), and Secondary Ion Mass Spectrometry (SIMS) has become well established for over the past 35 years. However, sputter depth profiling of organic and polymeric materials to quantify film thickness values and chemical and molecular compositions has required the introduction of cluster ion beam sources. Today the early excitement of the of cluster ion beam research is being complimented by routine XPS surface analyses. By combining a C₆₀ cluster ion beam with a scanning x-ray microprobe XPS today, a wide variety of organic depth profiling analyses have been performed. Highlights from a series of analyses on thick and thin polymer films will be presented. To extend the analytical accuracy and versatility of organic thin film analysis, the recent use of C₆₀ cluster ion beam and Ar ion beam co-sputtering of OLED materials will also be discussed.

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"High resolution X-ray tomography in the SEM"

     Dr. Paul Mainwaring, Gatan Inc.

The great advantage of SEM-based X-ray microscopy is the ability to image the internal structure of specimens rather than the surface information obtained by standard SEM imaging. The two techniques combine to provide the maximum amount of structural information.
The SEM-hosted X-ray ultra microscope (XuM) consists of 1) a series of metallic targets mounted on a high precision software-controlled positioning arm which is placed beneath the electron beam to produce a point source of X-rays; 2) a sample holder; and, 3) a high sensitivity CCD camera for X-ray detection. These components are fully compatible with the SEM working environment and allow switching between SEM and X-ray imaging modes without venting the specimen chamber. The desired X-ray energy can be “tuned” to the particular sample by selecting the target material which will provide optimal intensity and contrast in the images. This is particularly useful for certain low contrast specimens such as biological or polymer samples although suitably thinned steel samples have been recently examined.
Projection X-ray microscopy allows the sample to be always in focus and the great depth of field enables stereo imaging and 3D micro-tomography to be carried out. In general, spatial resolution of 200 – 400nm can be achieved for 2D imaging while tomographic resolution can be about 1um. The latter is dependent on SEM capability.
Recent improvements include custom built cameras for direct X-ray detection and robust phase contrast extraction algorithms, needed for low density sample imaging. In addition, a high resolution tomographic rotation stage and 3D reconstruction and visualization which can be completed in minutes add greatly to the power of this new technique. Full data acquisition and reconstruction can be completed in less than 3 hours.
Examples of the use of the X-ray microscope to image low atomic number materials and biological samples in 2-D and 3-D will be given.

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"Improving Thin Film Analysis in the SEM – New Methods for Measurement on the NanoScale"

     Dr. Neil Rowlands, Oxford Instruments.

The measurement of thin films is generally performed using indirect methods such as various gauges, large areas as in ellipsometry or by such highly sophisticated techniques as Rutherford Backscattering Spectrometry (RBS). Any measurements on a truly micro- or Nanoscale have involved destructive techniques e.g. physical cross sectioning or focused ion beam (FIB) cross sectioning methodology. Thin film ID enables the non destructive testing of nano-structured, layered materials of thicknesses varying between 2nm and 1000nm in the scanning electron microscope (SEM), equipped with an EDS analyzer, without the need to make cross sections. Multiple layers can be detected and measured in micro-areas of less than 1um allowing specific features to be measured without causing damage to the sample.

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