# 4.15 Tutorial sheet of chapter 2.semiconductor physics.

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This gives the tutorial sheet on Chapter 2-Semiconductor Physics.

Tutorial Sheet of Chapter 2.Semiconductor Physics.

Question 1. (a)Determine the Drift Velocity of electron and hole in the given intrinsic sample in Figure-Tutorial 2.1. with 10V applied across the junction?[vdrift(n)=5800cm/s,vdrift(p)=1800cm/s]Assume mobility given for intrinsic sample.

(b)Determine the conductivity of the following intrinsic sample?[σ=3*10 -6 S/cm]

(b) Determine the current flowing though the intrinsic sample?[0.72microA]

Question 2. The energy-band diagram is given in Figure-Tutorial2.2.

1. Calculate the probability of occupancy at Ed according to Fermi-Dirac Statistics? [P(Ed)=1.41%]
2. Calculate the % of ionization of Donor Atoms ? [99%]
3. If N C = effective density of states at E C = 3.01×10 19 /cc then calculate n n - ? [6.3917×10 16 /cc]
4. Calculate p n - if N V = effective density of states at E V = 1.04×10 19 /cc ? [2773.81]
5. Calculate n i 2 ? [(1.15×10 10 ) 2 ]
6. Calculate N D [6.3917×10 16 /cc ]

Question 3 .In a P-Type material, E F -E V = 0.1 eV and E a -E V =0.045eV.

Calculate the % of ionization of Acceptor Atoms ? [89%]

Question 4 .There is a compensated P-Type material at 300K. Minority carrier concentration is measured to be n p - =10 6 /cc. Acceptor Dopent Concentration = 10 15 /cc.

1. Determine majority carrier concentration? [10 14 /cc].
2. Determine N d ?[9×10 14 /cc].
3. Determine the total scattering centers.[ 19×10 14 /cc ].

Question 5. In Copper, resistivity= ρ = 1.67×10 -8 Ω-m and conductivity = σ = 6×10 7 S/m=qμn and n=8.5×10 22 /m 3 . Determine electron mobility ? [40 cm 2 /(V-s) ]

Question 6. In a 3 m long Cu Wire R = 0.03Ω and I = 15A through the wire.

1. Determine V drop across the wire ? [0.45V]
2. Determine E along the z-axis ? [0.15V/m]
3. Determine drift velocity of electron if μ= 40 cm 2 /(V-s)? [0.6×10 -3 m/s]
4. Determine the Fermi-velocity of conducting electron ? [10 6 m/s]
5. Determine the mean free time between two scatterings also defined as relaxation time ? [2.27×10 -14 s]
6. Determine the mean free path ?[275A°]. Compare this with lattice constant a =3.6A°.

Question 7. Typical N-Type resistivity ρ S =1Ω-cm.Typical current density 100A/cm 2 . mobility of electrons=1000cm 2 /V-s

1. Calculate E ? [100V/cm]
2. Calculate drift velocity ? [1.0×10 5 cm/s]

Question 8 .In a P-Type Sample , E=10 3 V/cm is applied. Determine drift velocity, mean free time and mean free path ? Assume μ p = 470 cm 2 /(V-s).

[Drift velocity = 4.7×10 5 cm/s which is much lower than thermal velocity of holes=2.2×10 7 cm/s; τ = 0.1ps, Mean Free Path = 220A°]

Question 9. The effective mass of electron and hole in semi-conductor is different from the mass in free space . Why?

The electrons and holes in a crystal interact with the periodic Coulombic Field in the Crystal. They surf over the periodic potential variation of the crystal lattice in the process developing roller coaster effect which leads to drastic reduction in effective mass.

Si Ge GaAs InAs AlAs
m n /m 0 0.26 0.12 0.068 0.023 2.0
m p /m 0 0.39 0.30 0.50 0.30 0.3

m n /m 0 = effective mass of electron/free space mass of electron

m p /m 0 = effective mass of hole/free space mass of hole.

In Silicon, using the effective mass of electron and holes the thermal velocity = 2.5×10 7 cm/s. Scatter Limit Velocities of electron and hole are of the same order.

how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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 ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
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
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
how did you get the value of 2000N.What calculations are needed to arrive at it
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