# 4.11 Chapter2.2.3;2.2.4;2.2.5;insulator,semi-conductor,metal  (Page 2/3)

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Here N C = effective density of states at E C (the lower edge of Conduction Band) ~10 19 /cc for all the three semiconductors namely Ge,Si and GaAs.

Here N V = effective density of states at E V (the upper edge of Valence Band) ~10 19 /cc for all the three semiconductors namely Ge,Si and GaAs.

E g = Band-Gap(eV), k = Boltzmann Constant, T = Absolute Temperature in Kelvin.

Table 2.2.4.1 gives the intrinsic concentration of electrons and holes in Ge,Si and GaAs at Room Temperature (300K).

Table 2.2.4.1. Intrinsic Concentration of electrons and holes in Ge,Si and GaAs at Temperature 300K.

Semiconductor Band-Gap Temperature Effective Density of States n i = p i
Ge 0.67eV 300K ~10 19 /cc 2.4×10 13 /cc
Si 1.12eV 300K ~10 19 /cc 4×10 9 /cc
GaAs 1.4eV 300K N C ~5×10 17 /cc, N V ~7×10 18 /cc 3.3×10 6 /cc

Figure 2.2.24 in the previous section illustrates how the EHP are thermally generated and why they are always equal.

Equation 2.2.3.1 clearly shows that intrinsic concentration is very temperature sensitive.

Table.2.2.4.2.Intrinsic Concentration of Si from 300K to 360K

Temperature 300K 310K 320K 330K 340K 350K 360K
Intrinsic Conc(per cc) 4×10 9 8×10 9 1.5×10 10 2.8×10 10 5×10 10 9×10 10 1.45×10 11

From Table 2.2.4.2 it is evident that for an increment of 60K above Room Temperature, intrinsic concentration has increased by two-orders of magnitude i.e. nearly 100 times. Because of this undesirable feature of intrinsic concentration, Si suffers from a very serious drawback namely: the reverse leakage current in a reverse biased diode doubles for every 10K rise in temperature.

In Figure 2.2.26, the exponential rise in intrinsic concentration with temperature is plotted.

2.2.5. Extrinsic Semi-conductor, space-charge neutrality and compensation .

Electronic Grade Semiconductor with no doping is called Intrinsic Semiconductor and that with doping is called Extrinsic Semiconductor.

Semiconductor is Group IV element or compound semi-conductor is Group (III+V) Compound.

For Group IV element, Group III(namely B, Al) is acceptor or P-Type dopent and Group V(P, As) is donor or N-Type dopent.

For Group (III+V)Compound semiconductor, Group II is acceptor or P-Type dopent and Group VI is donor or N-Type dopent.

In Figure 2.2.27, the consequence of introducing a donor atom or the consequence of introducing an acceptor atom in a Silicon Crystalline Lattice is shown.

In case of Donor doped Silicon where doping density is N D donor atoms/cc , the octave condition is completed by 4 valence electrons of donor atom hence 5 th valence electron beomes the odd-man out and hence is very loosely held by the host donor atom. At Room Temperature, the 5 th valence electron is broken loose from the donor and becomes a wanderer in Si-lattice. In effect Donor atom gets (+)ve ly ionized and donates its negatively charged 5 th valence electron to the Si-lattice.Hence overall space-charge neutrality is maintained. Plus there are thermally generated EHP also.Overall thermal equilibrium is achieved and we have thermal equilibrium concentration value(n n -bar) of conducting electron and thermal equilibrium value (p n -bar) of holes. Here conducting electrons are many orders of magnitude larger than holes hence electrons are referred to as majority carriers and holes are referred to as minority carriers.

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
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
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
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
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
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?
what is a peer
What is meant by 'nano scale'?
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 ?
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?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
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
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