# Chapter 33 Solids¶

## Example 33.1 Page no 904¶

In [6]:
#Given
Eg=0.72*1.6*10**-19                     #J
h=6.62*10**-34
c=3*10**8

#Calculation
L=(h*c)/Eg

#Result
print"The maximum wavelength of electromagnetic radiation is",round(L*10**6,3)*10**-6,"m"

The maximum wavelength of electromagnetic radiation is 1.724e-06 m


## Example 33.2 Page no 904¶

In [9]:
#Given
n1=1.5*10**16                    #/m**3
nh=4.5*10**22

#Calculation
ne=n1**2/nh

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

ne in the doping silicon is 5.0 *10**9 /m**3


## Example 33.3 Page no 904¶

In [16]:
#Given
ne=8*10**19                      #/m**3
nh=5*10**18
ue=2.3                                #m**2/V/S
uh=0.01
e=1.6*10**-19

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

#Result
print"(a) The semiconductor has greater electron concentration, it is n-type semiconductor"
print"(b) Resistivity is", round(a*10**2,3),"*10**-2 ohm/m"

(a) The semiconductor has greater electron concentration, it is n-type semiconductor
(b) Resistivity is 3.396 *10**-2 ohm/m


## Example 33.4 Page no 904¶

In [23]:
#Given
e=1.6*10**-19                      #C
A=500                              #ohm**-1 m**-1
Ue=0.39                            #m**2 V**-1 s**-1

#Calculation
Ne=A/(e*Ue)

#Result
print"The number density of donor atoms is",round(Ne*10**-21,3)*10**21,"m**3"

The number density of donor atoms is 8.013e+21 m**3


## Example 33.5 Page no 904¶

In [30]:
#Given
F=1.6*10**-19                       #E
W=4.2*10**8
e=2.4
w=4.2*10**-8

#Calculation
S=F*W
A=S/F
E=e/w

#Result
print"Electric field is", round(E*10**-7,2),"*10**7 V/m"

Electric field is 5.71 *10**7 V/m


## Example 33.6 Page no 904¶

In [33]:
#Given
h=6.62*10**-34
c=3*10**8
l=630*10**-9
e=1.6*10**-19

#Calculation
Eg=(h*c)/(l*e)

#Result
print"Width of the forbidden energy gap is",round(Eg,2),"eV"

Width of the forbidden energy gap is 1.97 eV


## Example 33.7 Page no 904¶

In [48]:
#iven
A=10**-4                         #m**2
l=0.1                            #m
V=2                               #V
T=300                             #K
ue=0.135                           #m**2/V/S
n=1.5*10**15                       #/m**3
uh=0.048                           #m**2/V/S
e=1.6*10**-19
ue1=0.39
uh1=0.19
n1=2.4*10**19

#Calculation
E=V/l
ve=ue*E
vh=uh*E
Ie=e*A*n*ve
Ih=e*A*n*vh
I=Ie+Ih
ve1=ue1*E
ve2=uh1*E
Ie1=e*A*n1*ve1
Ie2=e*A*n1*ve2
I1=Ie1+Ie2

#Result
print"Electron current is", Ie*10.0,"A \nHole current is",Ih*10,"A"
print"Magnitude of total current is",I*10,"A \nTotal current when germanium is used is",I1*10**3,"*10**-3 A"

Electron current is 6.48e-07 A
Hole current is 2.304e-07 A
Magnitude of total current is 8.784e-07 A
Total current when germanium is used is 4.4544 *10**-3 A