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Table.1.26.Properties of Elemental&Binary Compound Semiconductors at 300K.

Semiconductor Lattice Constant( a A° ) BandGap (E g eV) Band a Mobility b (cm 2 /V-s) DielectricConstant
Elemental μ n μ p ε r
Ge 5.64 0.66 I 3900 1900 16.0
Si 5.43 1.12 I 1450 450 11.9
IV-IV
SiC c 3.08 2.99 I 400 50 10.0
III-V
AlSb 6.13 1.58 I 200 420 14.4
GaAs 5.63 1.42 D 8500 400 13.1
GaP 5.45 2.26 I 110 75 11.1
GaSb 6.09 0.72 D 5000 850 15.7
InAs 6.05 0.36 D 33000 460 14.6
InP 5.86 1.35 D 4600 150 12.4
InSb 6.47 0.17 D 80000 1250 17.7
II-VI
CdS 5.83 2.42 D 340 50 5.4
CdTe 6.48 1.56 D 1050 100 10.2
ZnO 4.58 3.35 D 200 180 9.0
ZnS 5.42 3.68 D 165 5 5.2
IV-VI
PbS 5.93 0.41 I 600 700 17.0
PbTe 6.46 0.31 I 6000 4000 30.0

a I = Indirect, D = Direct;

b The values are for drift mobilities obtained in the purest and the most perfect materials available to date;

c Silicon Carbide crystallizes in the wurtzite structure.( Physics of Semiconductor Devices, S.M.Sze, 2 nd Edition, Wiley, New York, 1981.

1.11.6. BASIC CRYSTAL STRUCTURES.

The elemental semiconductors, Ge and Si, crystallize as diamond structure and most of the compound semiconductors crystallize as Zinc-Blende structure. These are variants of cubic structures.

We have three basic cubic structures: simple cube, body centered cube (bcc) and face centered cube (fcc). The side of a cube ‘a’ is known as lattice constant. The three parameters that characterize a cubic unit cell are : coordination number, the packing fraction and the nearest neighbor distance.

Polonium crystallizes as simple cube.

  • Each lattice center is occupied by one atom.
  • At each corner we have one atom and each corner atom is occupied by eight cubes. Hence unit cell has 8 corner atoms×(1/8)= 1 atom.
  • Coordination number is the number of nearest neighbor lattice site.
  • In simple cube it is 6. Four lattice sites lie in the same plane and two lie above and below the plane.
  • Packing fraction is {[(1/8)(4/3)πR 3 ]×8}/a 3 . Here a 3 is the volume of an unit cell. If we assume that the atom spheres are touching one another then R=a/2 where R is the radius of the atom. Therefore packing fraction is π/6. The nearest neighbor distance is ‘a/2’.

Sodium and Tungsten crystallize as Body Centered Cube(bcc).

  • This has one extra atom at the body center.
  • This amounts to [8 corner atoms×(1/8) + 1] = 2 atoms per cell.
  • The coordination number is 8 as the nearest neighbor atoms are the 8 body center atoms residing in the 8 unit cells surrounding each corner atom.
  • Therefore nearest neighbor distance a√3/2.
  • If we assume that the body center atom is touching the corner atom then the radius is R= a√3/4.
  • Therefore packing factor = (volume of 2 atoms)/a 3 = [2×(4/3)πR 3 ]/a 3 = [2×(4/3)π(a√3/4) 3 ]/a 3 =π√3/8= 0.68.

Aluminum, copper, gold and platinum crystallize as Face Centered Cube(fcc) .

  • Here there are no body centered atom. Instead there are 6 atoms at the center of the 6 faces of the cube.
  • This amounts to [8 corner atoms×(1/8) + 6 face atoms×(1/2) ] = 4 atoms per unit cell.
  • The corner atom lies at the intersection of 3 orthogonal planes. Each plane has four faces and each face has one atom at the center which is the nearest neighbor. Hence the coordination number is 12. Nearest neighbor distance is a√2/2 and the radius R = a√2/4. The packing factor is = (volume of 4 atoms)/a 3 = [4×(4/3)πR 3 ]/a 3 = [4×(4/3)π(a√2/4) 3 ]/a 3 = π√2/6= 0.74.

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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