MSRC

Field-Emission Scanning Electron Microscope (FE-SEM)

Quanta 3D FEG

The Quanta 3D FEG is the most versatile, high-resolution, low vacuum SEM/FIB for 2D and 3D material characterization and analysis.
The Quanta 3D FEG's novel, field-emission electron source delivers clear and sharp electron imaging and increased electron beam current enhances EDS analysis.

High-vacuum mode : < 6e-4 Pa
Low-vacuum mode : 10 to 130 Pa
ESEM-vacuum mode : 10 to 4000 Pa
Pump-down time (high-vacuum) :< 3minutes

Electron beam resolution

2.9 nm at 1 kV (SE)
Low-vacuum
1.5 nm at 30 kV (SE)
2.5 nm at 30 kV (BSE)
2.9 nm at 3 kV (SE)
Environmental SEM (SE)
1.5 nm at 30 kV (SE)

Basic modes of operation :

High vacuum mode:: allows the observation of translation patterns (eg., non-metallic samples or samples that are coated with a conductive layer (Ag, Au or C)).
Low vacuum :: allows the observation of translation as well as non-sample without prior preparation (polymer materials, ceramics, non-surface layers, some of the biological and medical samples, ...). The low vacuum is used to prevent electrical tamping the sample.
ESEM mode:: vacuum chamber with low added gas, which has low ionization energy and allows the formation of additional "environmental" secondary electrons. These electrons to improve the resolution, which is in the low vacuum worse than in the high. The gas, which is normally added in the chamber is water vapour. In "ESEM" mode, you can observe all kinds of samples (polymer materials, ceramics, non-surface layers of biological and medical samples, ...), in particular, is important for the observation of wet, greasy and dirty samples, and the observation of in-situ processes (hydratization , dissolving ...).

Characteristic Information : SEM

Topography: The surface features of an object or "how it looks", its texture;direct relation between these features and materials properties.
Topography: The surface features of an object or "how it looks", its texture;direct relation between these features and materials properties.
Morphology: The shape and size of the particles making up the object; direct relation between these structures and materials properties.
Composition (EDAX): The elements and compounds that the object is composed of and the relative amounts of them; direct relationship between composition and materials properties.
Crystallographic Information: How the atoms are arranged in the object; direct relation between these arrangements and material properties.

Focused Ion Beam / Scanning Electron Microscope (FIB/SEM)

Finely focused beam of “Ga” ions with a diameter ~ 5 nm onto the sample surface by a set of electrostatic lenses.

low beam currents allows imaging and high beam currents sputter or mill the samples.

Surface collision with energetic ions leads to sputter the material which leaves the surface either as secondary ions or neutral atoms (substrate milling).

Ion beam is scanned across the sample surface and secondary electrons collected for imaging purposes with resolution in the nanometer range.

High primary ion beam enables precise milling, cutting, drilling and structuring at the nano level.

The integration of FESEM and focused ion beam technology into one FIB/SEM system.

High resolution transmission electron microscope (HRTEM) :

High resolution transmission electron microscope (HRTEM), FEI TecnaiTM G2 F20 (S-TWIN), meets the most stringent demands of materials research on the morphology, crystallography and elemental compositions as well as the electronic structure of defects, interfaces, surfaces, grain boundaries and phases presenting in metals, ceramics, semiconductors, multi-layers, and polymers.
In TEM, a very high-energy electron beam is placed on a sample that is thin enough (100 nm) to be partially electron transparent, and the electron “shadow” of the sample is viewed and recorded either on film or by computer.
The TEM can magnify specimens up to 1 million times with point-to-point resolution of better than 2 nm. Sample preparation for TEM analysis is critical. Samples must be extremely thin or made extremely thin to allow for the electron beam to completely penetrate a sample.
Using energy dispersive x-ray spectrometry (EDS), bright field and dark field imaging and electron diffraction, our TEM capabilities can be used to characterized and identify a wide range of materials. The instrument also provides high-resolution performance in micro-analysis and (S)TEM imaging that is an increasing need for structural and compositional analysis of sub-nanometer structures.

Features:

Flexible accelerating voltage (20-200 kV)
Schottky field emitter with high maximum beam current (> 100 nA)
0.24 nm point resolution in TEM mode
0.19 nm point resolution in STEM mode
TEM magnification range 25 X – 1,030 kX (TEM)and 150 X – 230 MX (STEM)
EDS solid angle 0.13 srad
40 deg specimen tilt with double tilt holder

Essential specifications Point resolution (nm) 0.24 Information limit (nm) sigma 0.15 HR STEM resolution (nm) 0.2 Cs objective (mm) 1.2 Cc objective (mm) 1.2 Focal length (mm) 1.7 Maximum eucentric tilt ± 40°	Electron Source Schottky Field emitter with high maximum beam current (> 100 nA) - High probe current (> 0.6 nA in a 1 nm spot) - Small energy spread (0.7 eV@200kV or less) - Spot drift < 1 nm/minute - High short and long term stability
STEM Fully embedded digital scan system available - Bright Field and Annular Dark Field mode - High sensitivity HAADF STEM detector available - Magnification range 200 x - 100 Mx	Micro-analysis Embedded EDX and EELS spectrum imaging available - Small probes (< 0.3 nm) - No spurious / system peaks
Specimen stage - Fully computer-controlled, eucentric side-entry, high stability Compu-Stage -Maximized tilts for any X, Y, Z,alpha, ß combination - X, Y movement 2 mm, specimen size 3 mm - Specimen recall reproducibility: sigma 0.5 μm (x, y) and sigma0.5° (alpha ilt) - Drift < 0.5 nm/minute	Vacuum 100 l/s Ion Getter Pump on specimen area for contamination-free observation and analysis - Turbo molecular pump for prepumping column, gun and specimen airlock - Vacuum levels: specimen chamber 1 x 10-5 Pa; gun 1 x 10-6 Pa - Automatic overnight degassing of anti-contaminator

Scanning Probe Microscopy(SPM)

Principle of Operation :-

Branch of microscopy for surface characterization that involves formation of images by scanning with a physical probe.
- Invented in 1981 by Binning and Rohrer to study surface properties
- Surface topography
- Density of states
- Electric and Magnetic domain studies
- Nanoindentation/Lithography to make patterns
- Local charge accumulation
Different modes of operation based force between tip and sample interaction:
- Contact mode Works in repulsive regime ofF-z curve
- Spring constant of the lever should be less then effective spring constantholding the atoms.
- Force ~10-9N
- Non contact mode operates beyond repulsive mode.
- Force ~10-12N
- Tapping mode operated in attractive regime of F-z curve.
- Tip is oscillated at high frequency/amplitude,this deflection of the tip due to surface morphology is detected.

Scanning Tunneling Microscope

The scanning tunneling microscope (STM) works by scanning a very sharp metal wire tip over a surface. By bringing the tip very close to the surface, and by applying an electrical voltage to the tip or sample, we can image the surface at an extremely small scale – down to resolving individual atoms.

The STM is based on several principles. One is the quantum mechanical effect of tunneling. It is this effect that allows us to “see” the surface. Another principle is the piezoelectric effect. It is this effect that allows us to precisely scan the tip with angstrom-level control. Lastly, a feedback loop is required, which monitors the tunneling current and coordinates the current and the positioning of the tip. This is shown schematically below where the tunneling is from tip to surface with the tip rastering with piezoelectric positioning, with the feedback loop maintaining a current setpoint to generate a 3D image of the electronic topography: