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Characteristics Symbol Units Ge Si GaAs Cu
Effective Density of States N c Cm^ -3 1.04×10^ 19 2.8× 10^ 19 4.7×10^ 17
N v Cm^ -3 6.1×10^ 18 1.02× 10^ 19 7×10^ 18
Energy Gap E g eV 0.68 1.12 1.42
Intrinsic Carrier concentration n i Cm^ -3 2.25×10^ 13 1.15× 10^ 10 1.6×10^ 6 8.5× 10^ 22
Effective mass m n (unit mass 9.11×10 -31 Kg) 0.33 0.33 0.068
m p (unit mass 9.11×10 -31 Kg) 0.31 0.56 0.56
Mobility μ n Cm^ 2 / (V-s) 3900 1350 8600 44
μ n Cm^ 2 / (V-s) 1900 480 250
Dielectric Constant ε r 16.3 11.8 10.9
Atomic Concentration Cm^ -3 4.42×10^ 22 5×10^ 22 4.42× 10^ 22 8.5× 10^ 22
Breakdown Field E BR V/cm 10^ 5 3×10^ 5 3.5×10^ 5

1.10.2.1. METALS ( with special reference to the mobility of conducting electrons and its implications for particle accelerators ).

Metal is a lattice of positive ions held together by a gas of conducting electrons. The conducting electrons belonging to the conduction band have their wave-functions spread through out the metallic lattice. The average kinetic energy per electron is (3/5)E F (This will be a tutorial exercise). Hence

=
1.93

where m* is the effective mass of the electron but we will assume it to be the free space mass.

Therefore:

……………. 1.94

Where

This velocity is not thermal velocity but velocity resulting from Pauli’s Exclusion Principle which essentially is the result of the ferm-ionic nature of electrons. Electrons tend to repel one another when confined in a small Cartesian Space. Electrons are claustrophobic.

Therefore mean free path =

…… 1.95

Where τ is mean free time.

Substituting the appropriate values for each metal, we get the mean free path for electron in their respective metals.

Table(1.10) Tabulation of the Fermi Energy, velocity, mean free time and mean free path of conducting electrons in their respective metals.

Metal E F Velocity(×10^ 5 m/s) τ (femtosec) L*(A°)
Li 4.7 9.96 9 90
Na 3.1 8.08 31 250
K 2.1 6.65 44 293
Cu 7.0 12.15 27 328
Ag 5.5 10.77 41 441.6

As we see from Table(1.10), the mean distance between two scatterers is 2 orders of magnitude greater than the lattice constant which is of the order of 5 A°. Hence lattice centers per se are not the scatterers but infact the disorderliness is what causes the scattering. The scatterers are thermal vibrations of lattice centers, the structural defect in crystal growth and the substitutional/interstitial impurities. This implies that with reduction in temperature mobile electrons will experience less scattering hence the metal will exhibit less resistivity leading to positive temperature coefficient of resistance. We will dwell upon this in Section (1.12).

1.10.2.2. SEMICONDUCTORS

Semiconductors are insulators initially. At low temperatures, all electrons are strongly bonded to their host atoms. Only at temperatures above Liquid Nitrogen that thermal generation of electron-hole pairs take place. So in semiconductors the situation is quite different as compared to that in metal. The conducting electrons and holes owe their mobility to thermal energy they possess in contrast to the conducting electrons in metal. On an average by Equipartition Law of Energy, the mobile carriers possess (1/2)kT thermal energy per carrier per degree of freedom. Since the carriers have 3 degrees of freedom hence they possess (3/2)kT average thermal energy per carrier.

Questions & Answers

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
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
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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