# Chapter 26 Semiconductors¶

## Example 26.1 Page no 1414¶

In [6]:
#Given
a=0.47
ue=0.39                         #m**2/volt sec
uh=0.19                         #m**2/volt sec
e=1.6*10**-19

#Calculation
a1=1/a
ni=a1/(e*(ue+uh))

#Result
print"Intrinsic carrier conceentration is", round(ni*10**-19,1)*10**19,"/m**3"

Intrinsic carrier conceentration is 2.3e+19 /m**3


## Example 26.2 Page no 1414¶

In [13]:
#Given
a=0.01
e=1.6*10**-19
ue=0.39

#Calculation
a1=1/a
Nd=a1/(e*ue)

#Result
print"Donor concentration is", round(Nd*10**-21,1)*10**21,"/m**3"

Donor concentration is 1.6e+21 /m**3


## Example 26.3 Page no 1414¶

In [17]:
#Given
ni=2.5*10**19                           #/m**3
e=1.6*10**19
ue=0.36                                #m**2/volt sec
uh=0.17

#Calculation
a=ni*e*(ue+uh)

#Result
print"Conductivity is", a*10**-38,"S/m"

Conductivity is 2.12 S/m


## Example 26.4 Page no 1414¶

In [26]:
#Given
ne=8*10**13                         #/cm**3
nh=5*10**12                         #/cm**3
ue=23000                            #cm**2/vs
e=1.6*10**-19
uh=100                               #cm**2/vs

#Calculation
a=e*((ne*ue)+(nh*uh))
A1=1/a

#Result
print"(i) Since electron density is greater than the hole density, the semiconductor is n-type"
print"(ii) Resistivity of the sample is", round(A1,3),"ohm cm"

(i) Since electron density is greater than the hole density, the semiconductor is n-type
(ii) Resistivity of the sample is 3.396 ohm cm


## Example 26.5 Page no 1415¶

In [29]:
#Given
ni=1.5*10**16                      #/m**3
nh=4.5*10**22                      #/m**3

#Calculation
ne=ni**2/nh

#Result
print"ne in the doped semiconductor is",ne*10**-9,"*10**9 /m**3"

ne in the doped semiconductor is 5.0 *10**9 /m**3


## Example 26.6 Page no 1415¶

In [32]:
#Given
l=5890.0                          #A

#Calculation
E=12400/l

#Result
print"Minimum energy is",round(E,1),"ev"

Minimum energy is 2.1 ev


## Example 26.7 Page no 1415¶

In [34]:
#Given
a=6*10**19
b=10**-7

#Calculation
A=a*b

#Result
print"Number of holes is",A

Number of holes is 6e+12


## Example 26.8 Page no 1415¶

In [39]:
#Given
E=0.65
a=10**-10

#Calculation
l=(12400*a)/E

#Result
print"Maximum wavelength of electromagnetic radiation is",round(l*10**6,1)*10**-6,"m"

Maximum wavelength of electromagnetic radiation is 1.9e-06 m


## Example 26.9 Page no 1416¶

In [45]:
#Given
a=5                 #/ohm/cm
ue=3900              #cm**2/vs
e=1.6*10**-19

#Calculation
Nd=a/(ue*e)

#Result
print"Number density of donor atom is",round(Nd*10**-15,2)*10**15,"/cm**3"

Number density of donor atom is 8.01e+15 /cm**3


## Example 26.10 Page no 1416¶

In [50]:
#Given
ni=1.5*10**16                   #/m**3
a=5*10**28
b=10.0**6

#Calculation
Ne=a/b
nh=ni**2/Ne

#Result
print"Number of Electrons is",Ne,"/m**3"
print"Number of holes is",nh*10**-9,"*10**9 /m**3"

Number of Electrons is 5e+22 /m**3
Number of holes is 4.5 *10**9 /m**3


## Example 26.11 Page no 1416¶

In [61]:
#Given
d=4.0*10*-8                #m

#Calculation
a=2/1.6*10**-19
E=-a/d

#Result
print"Electric field is", round(E*10**22,0),"*10**7 V/m"

Electric field is 4.0 *10**7 V/m