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COLLEGE OF ENGINEERING & TECHNOLOGY
: Electronics & Communication Engineering
Department
Lecture
:
Course
Course No.
Date
: Solid State Electronics
: EC 210
: 12/6/2013
Dr. Iman Gamal Morsi
Mark : 40
Time : 2 hours
Final Exam
Answer the following questions :
Question (1):
Select the correct answer. In case there is more than one correct answer, select the answer, which
you consider the best.
1.
Single crystalline material structure:
a. It consists of different groups; each group has a specific shape different
from the others.
b. The atoms are well organized and have periodic structures.
c. Non uniform structure.
2. Amorphous material structure:
a. It consists of different groups; each group has a specific shape different
from the others.
b. The atoms are well organized and have periodic structures.
c. Non uniform structure.
3. Simple cubic unit cell has the following specifications:
a. Eight atoms at the corners, six atoms at the faces, and the total number of
atoms/m3 is four atoms, such as Al.
b. Eight atoms at the corners, one atom at the center of cube and the total
number of atoms is two atoms/m3, such as Fe.
c. Eight atoms at the corners, the total number of atoms/m3 is one.
d.
Eight atoms at the corners, six atoms at the faces, four atoms at a distance
(1/4) from corners and the total number of atoms/m3 is eight atoms, such as
Ge.
4. Face centered cubic unit cell has the following specifications:
a. Eight atoms at the corners, six atoms at the faces, and the total number of
atoms/m3 is four atoms, such as Al.
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b. Eight atoms at the corners, one atom at the center of cube and the total
number of atoms is two atoms/m3, such as Fe.
c. Eight atoms at the corners, the total number of atoms/m3 is one.
d. Eight atoms at the corners, six atoms at the faces, four atoms at a distance
(1/4) from corners and the total number of atoms/m3 is eight atoms, such as
Ge.
5. Diamond unit cell has the following specifications:
a. Eight atoms at the corners, six atoms at the faces, and the total number of
atoms/m3 is four atoms, such as Al.
b. Eight atoms at the corners, one atom at the center of cube and the total
number of atoms is two atoms/m3, such as Fe.
c. Eight atoms at the corners, the total number of atoms/m3 is one.
d. Eight atoms at the corners, six atoms at the faces, four atoms at a distance
(1/4) from corners and the total number of atoms/m3 is eight atoms, such as
Ge.
6. The relation between the density (  m ) and the lattice parameter (a) is:
a.  m 
n x Mat
a 3 x Av
b.  m 
Av x N
Mat
e. Both a and b.
c.  m 
d.  m 
N Mat
Av
a 3 x Av
n x Mat
7. The relation between lattice parameter (a) and atomic radius (r) for a
simple cubic unit cell is:
a. r 
a
2
b. r 
a
3
c. r 
a
4
d. r 
a 3
4
8. The relation between lattice parameter (a) and atomic radius (r) for a body
centered cubic unit cell is:
4r
8r
a. a 
b. a 
3
3
c. a 
2r
3
d. a 
3
4r
9. The relation between lattice parameter (a) and atomic radius (r) for a face
centered cubic unit cell is:
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a. a 
4r
3
c. a 
3
4r
b. a 
4r
2
d. a 
2
4r
10. The relation between lattice parameter (a) and atomic radius (r) for a
diamond unit cell is:
a. a 
8r
b. a 
3
3
8r
8 3
r
d. a 
r
8 3
---------------------------------------------------------------------------- (10 Marks)
Question (2)
c. a 
1. Find the name of the plane which intercepts the three axes x, y, z at
1
1
2a,
b, c, sketch the plane and the parallel plane.
2
3
2. Aluminum (AL) has a density of about 2699 kg/m3. Its atomic weight is 26.97
gm/mole find:
a. How many atoms exist in l m2 of the solid.
b. The volume of the unit cube for this FCC metal.
c. The atomic radius of AL.
d. The mass of a single atom of AL.
------------------------------------------------------------------------- (15 Marks)
Question (3)
a. Derive the Schrodinger equations dependent and independent of
time.
b. For the Semiconductor material, find the following:
1.
Derive the expression of Fermi level in the intrinsic semiconductor.
2.
Derive the location of intrinsic Fermi level with respect to valance band.
3.
Derive the location of n-type Fermi level with respect to conduction band.
At room temperature the conductivity of a crystal of pure silicon is 5x 10-4
( m )-1. If the electron mobility is 0.14 m2/v.s and the mobility of hole is 0.05
m2/v.s, determine the concentration of the electron – hole pairs in the crystal. If
doping with donor atoms to give an impurity concentration of 1022 atoms/m3 is
carried out for silicon crystal,
Calculate:
4.
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1. The majority and minority carrier's concentrations.
2.
The resistivity of the new crystal at room temperature.
3. Calculate the position of Fermi energy level with respect to the intrinsic
Fermi energy level for the new crystal at room temperature.
-------------------------------------------------------------------- (15 Marks)
Some Physical Constants:
Boltzmann’s constant, KB = 1.38x 10-23 J/K, the electric charge q= 1.6 x 10-19
coulomb; Planck’s constant, h = 6.625x10-34 J-S; the electronic mass. Me = 9.1
x 10-31 Kg; and the proton mass, mp=1.67x10-27 Kg.
Good Luck ,,,
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