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Thin films of many other materials have also been grown using MBE methods. Silicon technology has cheaper methods of growth and so Si layers are not very popular. However, possible devices made of Si-Ge alloys have been grown. The II-VI compounds, have also been grown. Magnetic materials, such as Co-Pt and Fe-Pt alloys, have been grown in the hopes of providing better magnetic storage.

Analysis techniques

The most popular in-situ analysis technique for MBE-grown layers is reflection high energy diffraction (RHEED), see [link] . Electrons of energy 5 - 40 keV are directed towards the sample. They reflect from the surface at a very small angle (less than 3°) and are directed onto a screen. These electrons interact with only the top few atomic layers and thus provide information about the surface. [link] shows a typical pattern on the screen for electrons reflected from a smooth surface, in which constructive interference between some of the electrons reflected from the lattice structure results in lines. If the surface is rough, spots will appear on the screen, also. By looking at the total intensity of the reflected electron pattern, an idea of the number of monolayers deposited and how epilayers grow can be obtained. The island-type growth shown in this figure is an area of intense interest. These oscillations in intensity are gradually damped as more layers are grown, because the overall roughness of the surface increases.

Schematic illustrating the formation of a RHEED pattern.
RHEED diffraction pattern of a GaAs surface. Adapted from images by the MBE Laboratory in the Institute of Physics of the ASCR (http://www.fzu.cz/departments/surfaces/mbe/index.html).

Phase locked epitaxy takes advantage of the patterns of the oscillations to grow very abrupt layers. By sending the oscillation information to a computer, it can decide when to open or close the shutters of the effusion cell based on the location in the oscillation cycle. This technique self-adjusts for fluctuations in beam flux when the shutters are opened and can grow very abrupt layers.

Another analysis technique that can be used to study surface smoothness during growth is ellipsometry. Polarized laser light is reflected from the surface at a small angle. The polarization of the light changes, depending on the roughness of the surface.

Improved growth characteristics also require that the actual flux from the sources is measured. This is typically done with an ion gauge flux monitor, which is either used to measure residual beam that misses the substrate or is moved into the beam path for calibration when a new source is used. Because of the importance of clean substrate surfaces for low-defect growth, Auger spectroscopy is used following cleaning by sputtering. Auger spectroscopy takes place by ionizing an inner shell electron from an atom. When an outer shell electron then deexcites to the inner shell, the energy released can prompt the emission of another outer shell electron. The energy at which this occurs is characteristic of the atom involved and the signal can be used to detect impurities as small as 0.1%.

Bibliography

  • K. J. Bachmann, The Materials Science of Microelectronics , VCH (1995).
  • S. K. Ghandhi, VLSI Fabrication Principles: Silicon and Gallium Arsenide , 2nd Edition, Wiley-Interscience, NY (1994).
  • M. A. Herman and H. Sitter, Molecular Beam Epitaxy: Fundamentals and Current Status , Springer-Verlag (1989).
  • Y. Horikoshi, M. Kawashima, and H. Yamaguchi, Jpn. J. Appl. Phys. , 1986, 25 , L868.
  • J. H. McFee, B. I. Miller, and K. J. Bachmann, J. Electrochem. Soc. , 1977, 124 , 259.
  • T. Sakamoto, H. Funabashi, K. Ohta, T. Nakagawa, N. J. Kawai, and T. Kojima, Jpn. J. Appl. Phys. , 1984, 23 , L657.
  • W. T. Tsang, J. Crystal Growth , 1987, 81 , 261.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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Source:  OpenStax, Chemistry of electronic materials. OpenStax CNX. Aug 09, 2011 Download for free at http://cnx.org/content/col10719/1.9
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