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In 1980’s with the development of low attenuation optical fiber , short haul-heavy traffic and long haul communication turned towards Optical Fiber Communication. In communication there is a heavy premium on Band Width and Optical fiber could offer immense amount of BW at very low cost. This gave a tremendous boost to R&D in optoelectronic devices and optoelectronic chips. The material of choice could only be Compound Semiconductors and their alloys. The compound semiconductors are direct band-gap materials offering high radiative quantum efficiency.

Indium Antimonide (InSb) was the first III-V compound semiconductor to be discovered in 1950. Because of narrow band-gap, E g = 0.17eV, InSb is the suitable material for fabricating optoelectronic devices in far infrared spectrum because 0.17eV band-gap corresponds to critical wavelength λ c = (1.24/ E g )= 7.3μm. This critical wavelength will decide the optical emission and absorption wavelength.

The invention of semiconductor laser and the discovery of Gunn-Effect brought GaAs ( E g = 1.43eV) and InP ( E g = 1.35eV) to a position of eminence. The need for visible light Light Emitting Diodes by necessity led to the importance of GaP( E g =2.1 eV) and its alloys. 2.1eV band-gap corresponds to a critical wavelength of 0.59μm which falls in visible part of the spectrum. By suitable alloying , any critical wave length in the range 0.4μm to 0.7 μm can be achieved and 0.4μm to 0.7 μm is the visible part of the spectrum. The alloying process, to achieve a suitable critical wavelength, is known as BAND-GAP ENGINEERING. We will deal with this topic in PHOTONICS Chapter.

The choice of different Binary Compounds provides us a wide range of Band-gaps ranging from InSb of band-gap 0.17eV to SiC of band-gap 2.99eV. SiC enabled the fabrication of Blue Laser diodes which are used to sense the pixels of DVD (Digital Versatile Disc). The advent of DVD has greatly enhanced the storage capacity. CD stores 700MB whereas DVD stores 4GB and more.

Here it may also be pointed out that Extreme Ultra-Violet photolithography is enabling the fabrication of nano-electronics chips or realization of lateral feature size less than 100nm as required in Ultra-Large-Scale-Integrated (ULSI) Chips. This again is dependent upon research in very wide band-gap material typically a band-gap of 12.4eV corresponding to a critical wavelength of 0.1μm.

The ease of alloying Binary Compounds into Ternary Compounds such as AlGaAs and Quaternary Compound such as InGaAlAs makes the use of compound semiconductor in photonics very attractive and convenient.. The alloyed Binary compounds gives a continuous and monotonic variation in Band-gap energy according the stoichometric coefficient of the alloyed material. This continuous variation gives the Photonic Scientists a more varied option in terms of band-structure, electronic properties and optical properties. The alloying process can be achieved by Molecular Beam Epitaxy(MBE). This alloying process also enables the fabrication of Hetrostructure Junctions which is much more power efficient as compared to Homojunctions. Homojunctions are junctions formed by P type and N Type of same material whereas Hetrojunctions are formed by P Type and N Type of different materials. Table(1.26) tabulates the electronic properties of Compound Semiconductors.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
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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