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During the MBE process, growth can be monitored in situ by a number of methods:

Reflection high energy electron diffraction (RHEED), using forward scattering at grazing angle, which shows a maximum when there is a completed monolayer and a minimum when there is a partial layer as this produces more scattering;

Low energy electron diffraction (LEED), takes place in backscattering geometry and can be used to study surface morphology, but not during growth;

Auger electron spectroscopy (AES), records the type of atoms present;

Modulated beam mass spectrometry (MBMS), allows the chemical species and reaction kienetics to be studied.

Computer controlled shutters of each furnace allows precise control of the thickness of each layer, down to a single layer of atoms.

Intricate structures of layers of different materials can be fabricated this way e.g., semiconductor lasers, LEDs.

Before starting the epitaxial growth, in-situ cleaning of substrate is required. This is achieved by High Temperature Baking of the substrate. This decomposes and vaporizes the oxide layer over the substrate. The second method of in-situ cleaning is low energy ion beam of inert gas is used to sputter clean the surface. After the sputtering , low temperature anneal;ing is required to reorder the surface lattice system.

If there is a lattice mismatch between the substrate and the growing film, elastic energy is accumulated in the growing film. At some critical film thickness, the film may break/crack to lower the free energy of the film. The critical film thickness depends on the Young’s moduli, mismatch size, and surface tensions. Hence under heteroepitaxy, we must keep the thickness lower than critical film thickness.

Figure 14 shows the physics of epitaxial growth in MBE system. . The aim of this process is to enable sharp interfaces to be formed between one type of alloy and the next e.g. GaAs and AlAs, and thus create structures which may confine electrons and exibit 2-dimensiona l behaviour. Molecular Beam Epitaxy ( MBE ) is basically a sophisticated form of vacuum evaporation.

METAL ORGANIC CHEMICAL VAPOUR PHASE DEPOSITION>

The growth process in MOCVD (metal-organic CVD, also known as MOVPE metal-organic vapour phase epitaxy) is similar to MBE, but the atoms are carried in gaseous form to the substrate. GaAlAs growth is achieved by using a mixture of hydrogen as a carrier gas and organometallic precursors such as trimethyl galium and/or trimethyl aluminium together with arsine. The growth rate can be 10 times greater than in MBE, the process does not require ultra high vacuum and it can be scaled up from research to production of commercial devices relatively easily. However, the preparation of the gaseous mixtures has to be very carefully controlled so that as yet it is unclear which technique will eventully dominate. One advantage MOVPE has over MBE is in the ability to grow phosphorous containing alloys, once phosphorous has been introduced into an MBE chamber it is almost impossible to grom anything else! One disadvantage is that in situ monitoring is more difficult.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
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
hey
Giriraj
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
ya I also want to know the raman spectra
Bhagvanji
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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Solid state physics and devices-the harbinger of third wave of civilization. OpenStax CNX. Sep 15, 2014 Download for free at http://legacy.cnx.org/content/col11170/1.89
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