Chapter 3: Carrier Transport Phenomena

Example 3.1 Page 51

In [4]:
#initialisation of variable
from math import *
M=.1;#mobility
t=300;#kelvin
n=.26;
q=1.6*10**-19;#C
m=9.1*10**-31;#kg
v=100000;#m/s

#calculation
T=(n*m*M)/q;#mean free time
P=v*T;#mean free path

#result
print"mean free time is",round(T*10**12,3),"ps"
print"mean free path is",round(P*10**9,1),"nm"

mean free time is 0.148 ps
mean free path is 14.8 nm

Example 3.2 Page 54

In [5]:
#initialisation of variable
from math import *
D=10**16;#doping
n=1300;
q=1.6*10**-19;#Charge

#calculation
R=1/(D*n*q);#resistivity

#result
print"resistivity is",round(R,2),"ohm-cm"

resistivity is 0.48 ohm-cm

Example 3.3 Page 56

In [1]:
#initialisation of variable
from math import *
D=10**16;#doping
W=500;#width
A=2.5/1000;#area
I=1;#mA
B=10**-4;#Wb/cm^2
q=1.6*10**-19;#charge

#calculation
R=-1/(q*D);#hall coefficient
Vh=(R*I*B*W)/A;#hall voltage

#result
print"Hall voltage is",round(Vh/10000,2),"mV"

Hall voltage is -1.25 mV

Example 3.4 Page 58

In [6]:
#initialisation of variable
from math import *
T=300;#K
n1=10**18;#concentration
n2=7*10**17;#concentration
x=.1;#distance
D=22.5;#diffusion coefficient
q=1.6*10**-19;#charge

#calculation
Id=q*D*(n1-n2)/x;#diffusion current

#result
print"diffusion current density is",round(Id,2),"A/cm^2"

diffusion current density is 10.8 A/cm^2

Example 3.5 Page 59

In [1]:
#initialisation of variable
from math import *
E=50;#V/cm
x=1;#cm
t=.1#ms

#calculation
Vd=x/t;#drift velocity
u=Vd/E;
D=.0259*u;#diffusivity

#result
print"drift velocity is",round(Vd*1000,2),"cm/s"
print"diffusivity is",round(D*1000,2),"cm^2/s"

drift velocity is 10000.0 cm/s
diffusivity is 5.18 cm^2/s

Example 3.6 Page 63

In [7]:
#initialisation of variable
from math import *
n1=10**14;#concentration
n2=9.65*10**9;
n3=10**13;#hole-pair concentration
t=2;#time

#calculation
p=((n2)**2)/n1;
C=p+t*n3;#concentration

#result
print"change in minority carrier concentration is",round(C/10**13)*10**13,"cm^-3"

change in minority carrier concentration is 2e+13 cm^-3

Example 3.7 Page 71

In [6]:
#initialisation of variable
from math import *
t1=100;#time
t2=200;#time
f=5;#factor

#calculation
L=(t2-t1)/log(f/2**.5);#lifetime

#result
print"minority carrier lifetime is",round(L,0),"micro sec"

minority carrier lifetime is 79.0 micro sec

Example 3.8 Page 73

In [5]:
#initialisation of variable
from math import *
E1=4.05;#eV
E2=.2;#eV
n=2.86*10**19;#concentration
E3=.6;#eV

#calculation
N1=n*exp(-(E1+E2)/.0259);#electron density
N3=n*exp(-(E2+E3)/.0259);#electron density

#result
print"emitted electron density 1 is",round(N1/2,52),"is almost equals 0"
print"emitted electron density 2 is",round(round(N3/1000000)*10**6,2),"cm^-3"

emitted electron density 1 is 1e-52 is almost equals 0
emitted electron density 2 is 1000000.0 cm^-3