This document provides an overview of scanning tunneling microscopy (STM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It describes the basic principles and operation of STM, including how it uses a sharp tip and tunneling current to image surfaces at the atomic scale. It also discusses key aspects of SEM such as how it shoots a beam of electrons at a sample and builds an image from secondary electrons. Finally, it explains that TEM works by sending a beam of electrons through a sample and projecting the transmitted electrons to view internal structure at the nanoscale.
Electron beam is the ability of high energy of electrons to alter the chemical structures of the molecules and its used to either modify or destroy hazardous organic molecules. The electron beam radiation processing is a chemical reaction caused in a material by radiation irradiation. In the radiation processing, electron beam and gamma rays are mainly used
Electron beam is the ability of high energy of electrons to alter the chemical structures of the molecules and its used to either modify or destroy hazardous organic molecules. The electron beam radiation processing is a chemical reaction caused in a material by radiation irradiation. In the radiation processing, electron beam and gamma rays are mainly used
A Scanning Electron Microscope (SEM) is a powerful magnification tool that utilizes focused beams of electrons to obtain information. The high-resolution, three-dimensional images produced by SEMs provide topographical, morphological and compositional information makes them vital in science and industry.
Instrumentation presentation - Auger Electron Spectroscopy (AES)Amirah Basir
Group 5-AES
Normaizatul Hanissa Binti Hamdan
Amirah Binti Basir
-Introduction/Backgroud /History, fundamental/basic principle and
elaboration of the principle, related pictures, related
equations/expressions/derivations, components and it functions,
related models/brands, technologies and applications
Electron Microscopy - Scanning electron microscope, Transmission Electron Mic...Sumer Pankaj
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. A transmission electron microscope can achieve better than 50 pm resolution and magnifications of up to about 10,000,000x whereas most light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000x.
Electron microscopes are used to investigate the ultrastructure of a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. Industrially, electron microscopes are often used for quality control and failure analysis. Modern electron microscopes produce electron micrographs using specialized digital cameras and frame grabbers to capture the image.
It includes topics regarding the Electron and ion spectroscopy. It consist of results of minute research done on the topics like electron spectroscopy for chemical analysis, auger spectroscopy, secondary ion mass spectroscopy, surface spectroscopic techniques and is very helpful for the analysis and presentation point of view.
Today, scanning electron microscopy (SEM) is a versatile technique used in many
industrial labs, as well as for research and development. Due to its high lateral resolution, its great depth of focus and its facility for X-ray microanalysis, SEM is ofen
used in materials science – including polymer science – to elucidate the microscopic
structure or to differentiate several phases from each other.
Surface modification can be used to alter
or improve these characteristics, and so
surface analysis is used to understand
surface chemistry of material, and
investigate the efficacy of surface
engineering. From non-stick cookware
coatings to thin-film electronics and bioactive
surfaces, X-ray photoelectron
spectroscopy is one of the standard
tools for surface characterization.
A Scanning Electron Microscope (SEM) is a powerful magnification tool that utilizes focused beams of electrons to obtain information. The high-resolution, three-dimensional images produced by SEMs provide topographical, morphological and compositional information makes them vital in science and industry.
Instrumentation presentation - Auger Electron Spectroscopy (AES)Amirah Basir
Group 5-AES
Normaizatul Hanissa Binti Hamdan
Amirah Binti Basir
-Introduction/Backgroud /History, fundamental/basic principle and
elaboration of the principle, related pictures, related
equations/expressions/derivations, components and it functions,
related models/brands, technologies and applications
Electron Microscopy - Scanning electron microscope, Transmission Electron Mic...Sumer Pankaj
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. A transmission electron microscope can achieve better than 50 pm resolution and magnifications of up to about 10,000,000x whereas most light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000x.
Electron microscopes are used to investigate the ultrastructure of a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, metals, and crystals. Industrially, electron microscopes are often used for quality control and failure analysis. Modern electron microscopes produce electron micrographs using specialized digital cameras and frame grabbers to capture the image.
It includes topics regarding the Electron and ion spectroscopy. It consist of results of minute research done on the topics like electron spectroscopy for chemical analysis, auger spectroscopy, secondary ion mass spectroscopy, surface spectroscopic techniques and is very helpful for the analysis and presentation point of view.
Today, scanning electron microscopy (SEM) is a versatile technique used in many
industrial labs, as well as for research and development. Due to its high lateral resolution, its great depth of focus and its facility for X-ray microanalysis, SEM is ofen
used in materials science – including polymer science – to elucidate the microscopic
structure or to differentiate several phases from each other.
Surface modification can be used to alter
or improve these characteristics, and so
surface analysis is used to understand
surface chemistry of material, and
investigate the efficacy of surface
engineering. From non-stick cookware
coatings to thin-film electronics and bioactive
surfaces, X-ray photoelectron
spectroscopy is one of the standard
tools for surface characterization.
• The scanning tunneling Microscope is an electron microscope that transmits three - dimensional images of the electron cloud around the nucleus.
• 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.
electron scattering,SEM,TEM,tunnel effect and lensesKASHISHMANGAL2
it can give you the brief view about the effects and lense used for electron microscope i.e. SEM,TEM,electron scattering,tunnel effect,electrostatic lens and magnostatic lens
Scanning Probe microscopy (AFM and STM) head point
AFM: Configuration of AFM
Parts of AFM system and Principle of AFM
Three Modes of AFM
AFM Instrument
Advantage and disadvantage
STM
Schematic Diagram
AFM and STM
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In our conventional electronic devices we use semi conducting materials for logical operation and magnetic materials for storage, but spintronics uses magnetic materials for both purposes. These spintronic devices are more versatile and faster than the present one. One such device is Spin Valve Transistors (SVT).
Spin valve transistor is different from conventional transistor. In this for conduction we use spin polarization of electrons. Only electrons with correct spin polarization can travel successfully through the device. These transistors are used in data storage, signal processing, automation and robotics with less power consumption and results in less heat. This also finds its application in Quantum computing, in which we use Qubits instead of bits.
11. History
• The principle of electron tunneling was proposed by
Giaever
– I. Giaever: Energy gap in superconductors measured by
electron tunneling, Phys. Rev. Lett. 5 (1960) 147–148
• He envisioned that if a potential difference is applied to
two metals separated by a thin insulating film, a
current will flow because of the ability of electrons to
penetrate a potential barrier.
• To be able to measure a tunneling current, the two
metals must be spaced no more than 10 nm apart.
12. Principle of STM
The principle of the STM is straightforward. A
sharp metal tip (one electrode of the tunnel
junction) is brought close enough (0.3–1 nm)
to the surface to be investigated (the second
electrode) that, at a convenient operating
voltage (10 mV–1 V), the tunneling current
varies from 0.2 to 10 nA which is measurable.
The tip is scanned over a surface at a distance
of 0.3–1 nm, while the tunneling current
between it and the surface is measured.
13. Compact STM for use in controlled environments
2000, Toyohashi University of Technology, Japan
14. STM images
Graphite
Guanine
Adenosine
Source: BSc & MSc thesis of Mashiur Rahman, Toyohashi University of Technology
16. Scanning Tunneling Microscope (STM)
This method uses an
electric current
(tunneling current) that
begins to flow when a
very sharp tip moves
near to a conducting
surface and hovers at
about one nanometer
away.
17. • The tip (about the size of a single atom) sits on
a piezoelectric tube. When you apply voltage
to electrodes attached to this tube, you can
make teensy adjustments to keep the
tunneling current constant — which also
keeps the tip at a constant distance from the
sample while an area is scanned. The
movement of the piezoelectric tube is
recorded and displayed as an image of the
sample surface.
18. Binnig et al.’s Design
VT = bias voltage
Ø = average barrier height
(work function)
JT = tunnel current
A = constant 1.025 eV−1/2Å−1.
19. STM Operation
• STM for operation in ambient air, the sample is held in
position while a piezoelectric crystal in the form of a
cylindrical tube (referred to as PZT tube scanner) scans the
sharp metallic probe over the surface in a raster pattern
while sensing and outputting the tunneling current to the
control station.
• The digital signal processor (DSP) calculates the desired
separation of the tip from the sample by sensing the
tunneling current flowing between the sample and the tip.
• The bias voltage applied between the sample and the tip
encourages the tunneling current to flow. The DSP
completes the digital feedback loop by outputting the
desired voltage to the piezoelectric tube.
20. constant-current &constant-height mode
STM can be operated in
either the constant-current or
the constant-height
mode.The images are of
graphite in air.
Source: Springer Handbook of Nanotechnology by B. Bhushan
21. STM cantilever / tip
• Typically fabricated from metal
wires of tungsten (W), platinum-
iridium (Pt-Ir), or gold (Au).
• sharpened by grinding,cutting
with a wire cutter or razor blade,
field emission/evaporator,
ionmilling, fracture, or
electrochemical polishing/etching
Schematics of a) CG Pt-Ir
probe, and (b) CG Pt-Ir FIB
milled probe
22. STM Tips
• The two most commonly used tips are
– Pt-Ir (80/20) Iridium: tips are generally
mechanically formed and are readily available.
provide better atomic resolution than tungsten
tips.
– Tungsten wire: are etched from tungsten wire with
an electrochemical process. Tungsten tips are
more uniformly shaped and may perform better
on samples with steeply sloped features.
23. Mechanically cut and electrochemically
etched STM tips
A mechanically cut STM tip (left) and an electrochemically etched STM tip (right),
p.383 Springer Handbook of Nanotechnology
24. Sample should be conductive
• Samples to be imaged with the STM must be
conductive enough to allow a few
nanoamperes of current to flow from the bias
voltage source to the area to be scanned.
• In many cases, nonconductive samples can be
coated with a thin layer of a conductive
material to facilitate imaging.
• The bias voltage and the tunneling current
depend on the sample.
25. piezoelectric tube
• If you put electrodes on the opposite sides of
some crystals — quartz or topaz, for example —
and apply a voltage across the crystal, it will
expand or contract. Any movement of the crystal
in response to a voltage is called the piezoelectric
effect.
• The piezoelectric tube used in the scanning
tunneling microscope is simply a crystal that
expands or contracts depending upon the voltage
you apply to it.
26.
27. Scanning electron microscope (SEM)
• An SEM shoots a beam of electrons at whatever
you’re examining, transferring energy to the spot
that it hits. The electrons in the beam (called primary
electrons) break off electrons in the specimen. These
dislodged electrons (called secondary electrons) are
then pulled onto a positively charged grid, where
they’re translated into a signal.
• Moving the beam around the sample generates a
whole bunch of signals, after which the SEM can
build an image of the surface of the sample for
display on a computer monitor.
28. Using SEM
SEMs can ferret out quite a bit of information about the
sample:
• Topography: surface features such as texture
• Morphology: shape, size, and arrangements of the
particles that compose the object’s surface
• Composition: elements that make up the sample
(This can be determined by measuring the X-rays
produced when the electron beam hits the sample.)
29. Transmission electron microscope (TEM)
• It’s a kind of nano-scale slide projector: Instead of shining a
light through a photographic image the TEM sends a beam of
electrons through a sample.
• The electrons that get through then strike a phosphor screen,
producing a projected image: Darker areas indicate that fewer
electrons got through; lighter areas are where more electrons
got through
• A TEM can achieve a resolution of approximately 0.2
nanometers, roughly the size of many atoms.
• A TEM can produce images that show you just how the atoms
are arranged in a material.