Integrated Advanced Microscopy Facilities

The integrated advanced microscopy facilities at the Cornell Center for Materials Research offer a broad range of instruments supported by trained professional staff, who assist researchers as they prepare, image, and analyze their specimens. Students, faculty, and industrial scientists make use of the wide variety of electron and optical microscopes to characterize and image their specimens. The most advanced instruments—housed in specialized rooms to minimize such effects as vibration, electromagnetic fields, and temperature fluctuations—have reached levels of performance seldom found in laboratories. Three full-time staff members knowledgeable about the instruments, characterization techniques, and specimen preparation are available for consultation and training. Each staff member has areas of individual expertise and general knowledge about campus experimental resources. If you are in doubt as to which technique will best suit your needs, any of the managers can provide guidance and direction.

The principal instruments available in the CCMR Integrated Advanced Microscopy Facilities include

• Scanning Electron Microscopes (SEM)
• Transmission Electron Microscopes (TEM)
• Scanning Transmission Electron Microscopes (STEM)
• Electron Microprobe (EPMA)
• Focused Ion Beam System (FIB)

Manager John Grazul 607.592.8989 grazul@ccmr.cornell.edu	Manager John Hunt 607.255.3789 or 607.592.8990 hunt@ccmr.cornell.edu	Manager Malcolm "Mick" Thomas 607.255.0650 mt57@cornell.edu
Faculty Advisors Prof. David Muller, A&EP dm24@cornell.edu	Prof. John Silcox, A&EP js97@cornell.edu
Main Locations: SB-56 Bard Hall; F-3 Clark Hall; 150 Duffield Hall

SEM Microscopy

Scanning electron microscopes (SEM) scan a sample using a focused probe of electrons that is maneuvered back and forth across the sample. The interaction of the probe with the sample produces signals containing information about the sample’s surface, composition, and in some cases, crystallography. CCMR has two SEM’s available to users; training is available on each instrument. They share some common capabilities, including secondary electron detectors for surface imaging, backscattered electron detectors for composition-based imaging, and energy dispersive X-ray spectrometers (EDS) for qualitative and quantitative composition information. The unique features of each microscope are detailed below.

KECK FE-SEM, LEO 1550 (Schottky Field Emitter)—Clark Hall, Contact Mick Thomas
Imaging at very high resolution (1 nm at 20 KeV and 2.5 nm at 5 KeV) is possible with certain types of specimens. Its superb performance, particularly at low accelerating voltages (i.e. 0.5 to 3 KV), makes it especially suitable for imaging the surface detail of polymeric, biological, and other low-density materials
Secondary Electron Imaging
An in-lens secondary electron detector enables a very short working distance and responds to the lowest voltage secondary electrons.
Transmission Electron Imaging
TEM grids may be used in a special stage in conjunction with a detector below the specimen to obtain transmitted electron images.

Leica 440 SEM (W Filament)—Bard Hall, Contact John Hunt
Resolution is 6 nm at 30 KeV. At lower KVs the resolution degrades significantly more than the Keck FE-SEM.
Special Feature: Electron Backscatter Diffraction (EBSD)
Pristine or very carefully polished (i.e. using colloidal silica) surfaces with a minimum grain size of about one micron can be characterized according to each grain’s crystallographic orientation. This is accomplished using an HKL Nordlys detector and associated software for automated acquisition and orientation analysis.
Eucentric Tilting Specimen Stage
Tilting is eucentric at any working distance. This facilitates observation while tilting as high as 90 degrees, and is ideal for recording stereo pairs for 3-D viewing.

Surface structure of optical fiber drilled through with femtosecond laser pulses. Debris from the drilling can be seen scattered on the surface. Pulse energies for drilling were only 70 nJ, somewhat less than the kinetic energy carried by a fruit fly. Image by Chris Hensley, A&EP, using the FE-SEM: Zeiss 1550

TEM/STEM Microscopy

Transmission electron microscopes (TEM) and scanning transmission electron microscopes (STEM) provide data utilizing electrons that have passed through very thin specimens. TEMs illuminate the sample with a parallel electron beam, while STEMs form a focused probe that is scanned across the sample in a raster fashion. In both cases signals are generated that can provide high-resolution images and spectra detailing sample structure, composition, crystallography, and nearest-neighbor bonding. CCMR has some of the most advanced TEMs and STEMs available anywhere. Training is available on each instrument. They share some common capabilities, and each also has some unique capabilities detailed in the following pages.

FEI Tecnai F20 TEM/STEM—Duffield Hall, Contact John Grazul
200 kV field emission transmission electron microscope with monochromator. 1 Å in TEM and 1.4 Å in STEM. Equipped with new Gatan tridium spectrometer for electron energy loss spectroscopy spectra at high energy resolution <0.2 eV, optimized recording of energy filtered TEM elemental maps, EELS low-loss studies (e.g. band gap analysis), and chemical bonding information at nanometer resolution.
Tomography
The Tecnai is also able to do electron tomography, which produces 3-D structures from 2-D projections, by acquiring an image every 2 degrees at angles +/- 70 degrees. This is only possible using our tomography holder and specialized software.

FEI Tecnai T12 Spirit Twin TEM/STEM—Duffield Hall, Contact John Grazul
120 kV field emission transmission electron microscope. Used to analyze both inorganic and organic materials at the nanoscale. Equipped with an LaB6 filament, single and double tilt holder, an SIS Megaview III CCD camera, and a STEM dark field and bright field detector, along with analysis and imaging software. Similar to the 200kV Tecnai above, this instrument has the ability to do electron tomography and diffraction analysis.

Ultrahigh Vacuum Scanning Transmission Electron Microscope—Clark Hall, Contact Mick Thomas
Provides quantitative imaging and spectroscopic analysis of materials at very high spatial and energy resolution. Typical experiments include studies of interfaces and grain boundaries of semiconductors, III-V compounds, ceramics, superconductors, and metal alloys. Beam-sensitive materials can be quantitatively analyzed due to the high efficiency of the detectors.
Electron Energy Loss Spectroscopy (EELS)
EELS offers elemental identification and studies of nearest-neighbor bonding at the
atomic scale.
X-ray (EDX)
A windowless Si(Li) detector provides elemental analysis of the specimen from spatial sizes as small as 1nm.
High Resolution Imaging
Researchers have acheived point-to-point resolutions of ~0.2 nm, as well as a lattice fringe resolution of 0.2 nm. Energy filtered images may also be obtained.
Diffraction
Convergent beam electron diffraction (CBED), energy filtered CBED, and selected area diffraction (SAD) modes are available in the Clark Hall facility.

Nion SuperSTEM (Cs-Corrected Scanning Transmission Electron Microscope)—Duffield Hall, Contact Mick Thomas
The SuperSTEM has a spherical aberration corrector integrated into its column, which nulls all axial aberrations up to fifth order. As a result, an angstrom-scale probe with 0.1 nA of current will enable imaging with angstrom-level (0.1 nm) resolution. The electron optics can be quickly changed to produce a 2-3 angstrom probe with 1 nA or more of current for analytical purposes (electron energy loss spectroscopy).

Electron Microprobe

The electron microprobe is primarily used for elemental analysis of heterogeneous materials. The volume from which the characteristic X-ray signal emerges depends on the density of the material being analyzed and on the accelerating voltage of the electron beam. The smallest volume in many cases is on the order of one cubic micron. With five automated wavelength dispersive X-ray spectrometers, each spot analysis is normally completed within minutes of calibration. A comprehensive collection of standards is kept in the lab.

JEOL 8900 Electron Microprobe (EPMA)—Snee Hall, Contact John Hunt

• Samples should be flat and are frequently polished to one micron grit or better. Holders are available for round mounts measuring one inch, one inch and a quarter, or one inch and a half. A special holder for unusually shaped specimens is also available.
• Nonconductive specimens are normally coated with carbon using the Edwards evaporator located in SB56 Bard Hall.

Focused Ion Beam

A focused ion beam (FIB) is used for specimen preparation, imaging, and analysis. Its Ga+ ion beam rasters over the surface of a sample, like an electron beam in a scanning electron microscope (SEM). The secondary electrons or ions generated are collected to form an image of the surface of the sample. The ion beam is also able to mill into the sample at well-defined sites to produce cross-sectional images, to modify the sample structure, or to produce samples to be imaged in a transmission electron microscope (TEM). A “dual beam” system adds a scanning electron microscope column to the FIB column enabling simultaneous high resolution imaging and nanoscale cutting. Scanning transmission electron microscope (STEM) capabilities on an FIB enable high-resolution imaging using transmitted electrons without breaking vacuum.

FEI Strata 400 STEM Dual Beam Focused Ion Beam (FIB)—Duffield Hall, Contact Mick Thomas
The Strata 400 is a DualBeam™ system for high-resolution, high-contrast imaging and specimen preparation. It incorporates a field emission scanning electron microscope column and a focused ion beam column. A high-performance Flipstage/STEM assembly allows for complete in-situ sample preparation and high-resolution imaging of samples without breaking vacuum. Organic, inorganic, and novel materials that are not amenable to conventional preparation methods for SEM and TEM can be prepared.

X-ray maps showing the distribution of Al (red), Fe (green), and Si (blue) in the BEI image (upper left). Images by Gabriela Depine, E&AS, using the electron microprobe

Additional Microscopy Resources

Sample Preparation
TEM sample preparation equipment includes a multiprep tripod polisher, jet polisher, ultramicrotomy, plasma cleaner, disc cutter, dimpler, and ion mill for making thin TEM specimens, Au-Pd sputterer, ion-beam sputterer and evaporator for coating specimens with conductive films of metal or carbon. Microtomes are also located in the CCMR Hudson Mesoscale Facility.

Optical (Visible Light) Microscopes
Several light microscopes are available, with magnification from 7x to 500x. Reflected light microscopes have bright field, dark field, Nomarski differential interference contrast (DIC), and bright fluorescence imaging. Our newest microscope is an Olympus BX-51 with excellent cross-polarized transmitted light. Our new long working distance objectives may be used on this microscope or on our inverted microscope. A color digital camera is available for use on all of the microscopes.

Interferometer Surface Profiler
ADE Phase-Shift MicroXAM: non-contact surface profiler capable of characterizing 3-D microstructures such as microelectronic mechanical systems (MEMS). Measures roughness, finish, and texture of surfaces ranging from highly polished optics and wafers to rough surfaces such as rolled steel, aluminum, and ceramics.

Other Microscopy Resources in CCMR Facilities

Materials Facility: Clark Hall & Bard Hall

• Scanning probe microscopy: AFM, SPM, and other techniques
• Confocal/multiphoton microscopy (operated by NBTC)
• Stylus surface profilers for surface topography measurements
• Optical microscopes with digital camera

Molecular and Cellular Imaging Facility: Bard Hall

• Confocal Raman microscopy
• Near field scanning optical microscopy
• Ultrahigh vacuum scanning probe microscopy