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SSPD_Chapter 1_Part 11_continuation describes the crystal structure and its crystalline parameters.

SSPD_Chapter 1_ Part 11_Solid State of Matter continued_Silicon, Germanium and GaAs crystal structures


Before the advent of Solid State Technology, i.e. before 1950, semiconductor was used as two terminal point contact diode and photodiode. With the invention of Bipolar Junction Transistor, Germanium rose to the position of eminence because of its unusually high mobility of electron = 3900 cm 2 /(V-sec) [Table 1.10]. But with the invention of Integrated Circuit Chips it yielded ground to Silicon.

Today Silicon has become the staple of the Post- Industrial Society just as Iron became the staple of the Industrial Society.

Why Silicon has become the material of choice and the most studied semiconductor in Computer Era? It is primarily because of Silicon-dioxide layer which can easily be formed by oxidation either in dry Oxygen or in steam. Oxidation is the key process in I.C.Technology. SiO 2 acts as passivating layer as well as a shielding layer during diffusion. As we know that Silicon is a 3-D orderly arrangement of Silicon atoms which is abruptly terminated at the surface boundary of the crystal. This abrupt termination of orderly arrangement leaves many covalent bonds incomplete. These incomplete bonds are known as dangling bonds. These dangling bonds cause surface states and these surface states tend to trap or release mobile carriers. This random release or trapping of mobile carriers cause 1/f noise or flicker noise. Passivation of the surface states minimizes the flicker noise, stabilizes the electrical characteristics of the device and provides a protective layer to the underlying device. Since SiO 2 is a perfect insulator it is used for isolation of devices which considerably reduces the parasitic effects. Conventionally reversed biased diode is used which eats away a lot of the real estate on the Silicon Surface and gives rise to severe parasitic effects. The real estate is saved as well as parasitics are minimized by the use of SiO 2 as isolation layer as well as the substrate as it is done in Silicon - on - Insulator (SOI) Technology.

The second reason for the popularity of Silicon is easy and cheap availability. It is obtained from silica and silica comprises 25% of Earth’s crust. Silicon is second most abundant after oxygen.

But Silicon is most unsuitable for photonics because of indirect band-gap and its accompanying non-radiative transitions though in recent years Silicon has been suitably modified to obtain photonic circuits on Silicon Substrate. Because of the unsuitability of Silicon, we have had to opt for Compound Semiconductors and its alloy as shown in Table(1.25).

Table(1.25) give the compound semiconductors which have application in Photonics.

Table. 1.25. Compound Semiconductors for Photonics application.

Element IV-IV compounds. III-Vcompounds II-VIcompounds IV-VIcompounds
Si SiC AlAs CdS PbSe.
Ge AlSb CdSe
GaAs ZnS
GaP ZnSe
GaSb ZnTe

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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