In [2]:

```
import math
#Variables
R = 1000.0 #Resistance (in ohm)
sig = 5.8 * 10**7 #Conductivity in (Siemen per meter)
d = 10**-3 #diameter (in meter)
E = 10 * 10**-3 #Eletric field (in Volt per meter)
#Calculation
l = R *sig * math.pi * d**2 /4 #length (in meter)
J = sig * E #Current density (in Ampere per metersquare)
#Result
print "Length of wire is ",round(l/1000,2)," km.\nCurrent desity is ",J," A/(m*m)."
```

In [3]:

```
import math
#Variables
d = 2* 10**-3 #diameter (in meter)
sig = 5.8 * 10**7 #conductivity (in siemen per meter)
mu = 0.0032 #mobilty (in metersquare per volt-second)
E = 20 * 10**-3 #Electric field (in Volt per meter)
q = 1.6 * 10**-19 #Charge on electron (in Coulomb)
#Calculation
n = sig / (q * mu) #charge density (in cubic-meter)
J = sig * E #Charge density (in Ampere per square-meter)
A = math.pi * d**2 / 4 #Cross section of wire (in square-meter)
I = J * A #Current (in Ampere)
v = mu * E #Drift velocity (in meter per second)
#Result
print "Charge density of free electrons is ",round(n,3)," m**-3.\nThe current density is ",J," A/m**3.\nCurrent flowing in the wire is ",round(I,3)," A.\nElectron drift velocity is ",v," m/s."
```

In [4]:

```
import math
#Variables
n = 5.8 * 10**28 #number of free electrons (in per cubic-meter)
p = 1.54 * 10**-8 #resistivity (in ohm-meter)
q = 1.6 * 10**-19 #charge (in Coulomb)
m = 9.1 * 10**-31 #mass of electron (in kg)
#Calculation
sig = 1/p #conductivity (in siemen per meter)
mu = sig /(q * n) #mobility (in meter-square/volt-second)
t = mu * m / q #time (in second)
#Result
print "Mobility of electrons is ",round(mu,6)," m**2/V-s.\nRelaxation time is ",round(t*10**12,6)," ps."
#Calculation error in book.
```

In [31]:

```
import math
#Variables
un = 0.38 #mobility of electrons in germanium (in meter-square/volt-second)
up = 0.18 #mobility of holes in germanium (in meter-square/volt-second)
ni = n = p = 2.5 * 10**19 #mobile ions for germanium (in per cubic-meter)
un1 = 0.13 #mobility of electrons in germanium (in meter-square/volt-second)
up1 = 0.05 #mobility of holes in germanium (in meter-square/volt-second)
ni1 = n1 = p1 = 1.5 * 10**16 #mobile ions for germanium (in per cubic-meter)
q = 1.6 * 10**-19 #charge of electron (in Coulomb)
#Calculation
#for germanium:
sig = q * ni * (un + up) #Conductivity of germanium (in siemen per metre)
sig1 = q * ni1 * (un1 + up1) #Conductivity of silicon (in siemen per metre)
#Result
print "Intrinsic conductivity of germanium is ",sig," S/m and of silicon is ",sig1," S/m."
```

In [30]:

```
import math
#Variables
ni = 1.41 * 10**16 #intrinsic concentration (in per cubic-metre)
un = 0.145 #mobility of electrons in germanium (in metre-square/volt-second)
up = 0.05 #mobility of holes in germanium (in metre-square/volt-second)
q = 1.6 * 10**-19 #charge of electron (in Coulomb)
#Calculation
sig = q * ni * (un + up) #Conductivity of germanium (in siemen per metre)
#Result
print "Intrinsic conductivity of silicon is ",sig," S/m."
print "Contribution by electron is ",q*ni*un," S/m."
print "Contribution by electron is ",q*ni*up," S/m."
```

In [29]:

```
import math
#Variables
l = 0.2 * 10**-3 #length (in meter)
A = 0.04 * 10**-6 #Area of cross section (in square-meter)
V = 1 #Voltage (in volts)
I = 8 * 10**-3 #current (in Ampere)
un = 0.13 #mobility of electron (in m**2 per volt-second)
q = 1.6 * 10**-19 #charge on electron (in Coulomb)
#Calculation
R = V/I #Resistance (in ohm)
p = R * A/l #Resistivity (in ohm-meter)
sig = 1/p #Conductivity (in siemen per meter)
n = sig / (q * un) #concentration (in per cubic-meter)
J = I/A #current density (in Ampere per square-meter)
v = J/(n*q)
#Result
print "Concentration of free electrons is ",round(n,3)," m**-3.\nDrift velocity is ",v," m/s."
```

In [28]:

```
import math
#Variables
p = 0.47 #Resistivity (in ohm-meter)
q = 1.6 * 10**-19 #charge on electron (in Coulomb)
un = 0.39 #mobility of electron in germanium (in m**2 per volt-second)
up = 0.19 #mobility of hole in germanium (in m**2 per volt-second)
#Calculation
sig = 1/p #Conductivity (in siemen per meter)
ni = sig / (q *(un +up)) #intrinsic concentration (in per cubic-meter)
#Result
print "Intrinsic concentration is ",ni," m**-3."
```

In [27]:

```
import math
#Variables
ND = 10**21 #Donor concentration (in per cubic-meter)
NA = 5 * 10**20 #Acceptor concentration (in per cubic-meter)
un = 0.18 #mobility of electron in silicon (in m**2 per volt-second)
q = 1.6 * 10**-19 #charge on electron (in Coulomb)
#Calculation
n = ND -NA #net donor density (in per cubic-meter)
sig = n * q * un #Conductivity (in Siemen per meter)
#Result
print "Conductivity of silicon is ",sig," (ohm-meter)**-1."
```

In [26]:

```
import math
#Variables
p = 100.0 #resistivity (in ohm-meter)
q = 1.6 * 10**-19 #Charge on a electron (in Coulomb)
un = 0.36 #donor concentration (in per cubic-meter)
#Calculation
sig = 1/p #conductivity (in siemen per meter)
n = sig /(q * un) #intrinsic concentration (in per cubic-meter)
ND = n #Donor concentration (in per cubic-meter)
#Result
print "Donor concentration is ",ND," m**-3."
```

In [25]:

```
import math
#Variables
ND = 2 * 10**14 #Donor atom concentration (in atoms per cubic-centimeter)
NA = 3 * 10**14 #Acceptor atom concentration (in atoms per cubic-centimeter)
ni = 2.3 * 10**19 #intrinsic concentration (in atoms per cubic-centimeter)
#Calculation
n = ni**2 / NA #concentration of electrons (in electrons per cubic-centimeter)
p = ni**2 / ND #concentration of holes (in holes per cubic-centimeter)
#Result
print "Electron concentration is ",n," electrons/cm**3.\nHole concentration is ",p," holes/cm**3."
```

In [24]:

```
import math
#Variables
ND = 5 * 10**8 #Donor atom concentration (in atoms per cubic-centimeter)
NA = 6 * 10**16 #Acceptor atom concentration (in atoms per cubic-centimeter)
ni = 1.5 * 10**10 #intrinsic concentration (in atoms per cubic-centimeter)
#Calculation
n = ni**2/NA #number of electrons (in per cubic-centimeter)
p = ni**2/ND #number of holes (in per cubic-centimeter)
#Result
print "Density of electrons is ",n," cm**-3.\nDensity of holes is ",p," cm**-3."
```

In [23]:

```
import math
#Variables
d = 0.001 #diameter (in meter)
ND = 10**20 #Number of phosphorus ions (in per cubic-meter)
R = 1000 #Resistance (in ohm)
un = 0.1 #mobility (in meter-square per volt-second)
q = 1.6 * 10**-19 #charge on electron (in Coulomb)
#Calculation
n = ND #Number of free electron (in per cubic-meter)
sig = q*n*un #conductivity (in Siemen per meter)
A = math.pi * d**2 / 4 #Area of cross section (in meter-square)
l = R * sig * A #length (in meter)
#Result
print "Length of the silicon would be ",round(l*1000,3)," mm."
```

In [22]:

```
import math
#Variables
q = 1.6 * 10**-19 #Charge on electron (in Coulomb)
sig = 100.0 #Conductivity of Ge (in per ohm-centimeter)
sig1 = 0.1 #Conductivity of Si (in per ohm-centimeter)
ni = 1.5 * 10**10 #intrinsic conductivity for Si (in per cubic-centimeter)
un = 3800.0 #mobility of electrons for Ge (in square-centimetermeter per volt-second)
up = 1800.0 #mobility of holes for Ge (in square-centimeter per volt-second)
un1 = 1300.0 #mobility of electrons for Si (in square-centimetermeter per volt-second)
up1 = 500.0 #mobility of holes for Si (in square-centimeter per volt-second)
ni1 = 2.5 * 10**13 #intrinsic concentration for Ge (in per cubic-centimeter)
#Calculation
p = sig / (q * up) #Concentration of p-type germanium (in cubic-centimeter)
n = ni1**2 / p #Concentration of electrons in germanium (in cubic-centimeter)
n1 = sig1 / (q * un1) #Concentration of N-type silicon (in cubic-centimeter)
p1 = ni**2 / n1 #Concentration of holes in silicon (in cubic-centimere)
#Result
print "For p-type germanium, hole concentration is ",p,"/cm**3.\nFor p-type germanium, electron concentration is ",n,"/cm**3."
print "For n-type silicon, hole concentration is ",p1,"/cm**3.\nFor n-type silicon, electron concentration is ",n1,"/cm**3."
```

In [21]:

```
import math
#Variables
un = 3800 #mobility of electrons (in centimeter-square per volt-second)
up = 1800 #mobility of holes (in centimeter-square per volt-second)
ni = 2.5 * 10**13 #intrinsic concentration (in per cubic-centimeter)
Nge = 4.41 * 10**22 #concentration of germanium (in per cubic-centimeter)
q = 1.6 * 10**-19 #charge on electron (in Coulomb)
#Calculation
ND = Nge/10**8 #Number of donor atoms (in per cubic-centimeter)
p = p = ni**2/ND #Number of holes (in per cubic-centimeter)
sig = q * ND * un #Conductivity of n-type germanium (in per ohm-centimeter)
p = 1/sig #resistivity (in ohm-centimeter)
#Result
print "resistivity of the germanium sample is ",round(p,3)," ohm-cm."
```

In [14]:

```
import math
#Variables
un = 1350 #mobility of electrons (in centimeter-square per volt-second)
up = 480 #mobility of holes (in centimeter-square per volt-second)
ni = 1.52 * 10**10 #intrinsic concentration (in per cubic-centimeter)
Nsi = 4.96 * 10**22 #concentration of silicon (in per cubic-centimeter)
q = 1.6 * 10**-19 #charge on electron (in Coulomb)
#Calculation
sigi = q * ni * (un + up) #conductivity of intrinsic silicon (in per ohm-centimeter)
p = 1/sig #resitivity (in ohm-centimeter)
ND = Nsi/(50 * 10**6) #Number of donor atoms (per cubic-centimeter)
n = ND #NUmber of free electrons (in per cubic-centimeter)
p = ni**2/n #number of holes (in per cubic-centimeter)
sig = q * n * un #conductivity of doped silicon (in per ohm-centimeter)
p = 1/sig #resistivity (in ohm-centimeter)
#Result
print "Resistivity of doped silicon is ",round(p,2)," ohm-cm."
```

In [3]:

```
#Variables
up = 0.048 #hole mobility (in meter-square per volt-second)
un = 0.135 #electron mobility (in meter-square per volt-second)
q = 1.602 * 10**-19 #charge on electron (in Coulomb)
Nsi1 = 5 * 10**28 #concentration of intrinsic silicon (in atoms per cubic-meter)
ni = 1.5 * 10**16 #number of electron-hole pairs (per cubic-meter)
alpha = 0.05 #temperature coefficient (in per degree Celsius)
dT = 14 #change in temperature (in degree celsius)
#Calculation
sig1 = q * ni * (un + up) #conductivity of intrinsic silicon (in per ohm-meter)
NA = Nsi1/10**7 #Number of indium atoms (in per cubic-meter)
p = NA #Number of holes (in per cubic meter)
n = ni**2/p #Number of free electrons (in per cubic-meter)
sig2 = q * p * up #Conductivity of doped silicon (in per ohm-meter)
sig34 = sig1*(1 + alpha * dT) #Conductivity at 34 degree Celsius (in per ohm-meter)
#Result
print "Conductivity of intrinsic silicon is ",round(sig1,5)," per ohm-meter.\nConductivity of doped Silicon is ",round(sig2,2)," per ohm-meter.\nConductivity of silicon at 34 degree Celsius is ",round(sig34,5)," per ohm-meter."
```

In [2]:

```
import math
#Variables
un = 3600.0 * 10**-4 #mobility of electrons (in meter-square per volt-second)
up = 1700.0 * 10**-4 #mobility of holes (in meter-square per volt-second)
k = 1.38 * 10**23 #Boltzmann constant
T = 300.0 #Temperature (in kelvin)
#Calculation
VT = T/11600 #Voltage (in volts)
Dp = up * VT #Coefficient of holes (in meter-square per second)
Dn = un * VT #Coefficient of electrons (in meter-square per second)
#Result
print "Coefficient of holes is ",round(Dp,6)," m**2/s.\nCoefficient of electrons is ",round(Dn,4)," m**2/s."
#un and up in book should be in (cm**2/V-sec)
```

In [19]:

```
import math
#Variables
RH = 160 #Hall coeffficient (in cubic-centimeter per Coulomb)
p = 0.16 #Resistivity (in ohm-centimeter)
#Calculation
sig = 1/p #Conductivity (in per ohm-centimeter)
un = sig * RH #Electron mobility (in cmentimeter-square per volt-second)
#Result
print "Electron mobility is ",un," cm**2/V-s."
```

In [18]:

```
import math
#Variables
I = 50 #Current (in Ampere)
B = 1.2 #Magnetic field (in Weber per meter-square)
t = 0.5 * 10**-3 #thickness (in meter)
VH = 100 #Hall coltage (in volts)
q = 1.6 * 10**-19 #Charge on electron (in Coulomb)
#Calculation
n = B * I / (VH * q * t) #number of conduction electrons (in per cubic-meter)
#Result
print "Number of conduction electrons is ",n," m**-3."
```

In [17]:

```
import math
#Variables
p = 20 * 10**-2 #Resistivity (in ohm-meter)
u = 100 * 10**-4 #mobility (in meter-square per volt-second)
#Calculation
sig = 1/p #Conductivity (in per ohm-meter)
n = sig / (q * u) #number of electron carriers (in per cubic-meter)
#Result
print "Number of electron carriers is ",round(n,1)," m**-3."
```

In [1]:

```
import math
#Variables
RH = 3.66 *10**-4 #Hall coefficient (in cubic-meter per Coulomb)
p = 8.93 * 10 **-3 #Resistivity (in ohm-meter)
q = 1.6 * 10**-19 #Charge on electron (in Coulomb)
#Calculation
sig = 1/p #Conductivity (in per ohm-meter)
u = sig * RH #mobility (in meter-square per volt-second)
n = 1 / (RH * q) #Density of charge carriers (in per cubic-meter)
#Result
print "Mobility of charge carriers is ",round(u,3)," m**2/V-s.\nDensity of charge carriers is ",n," m**-3."
```

In [15]:

```
import math
#Variables
p = 9 * 10**-3 #Resistivity (in ohm-meter)
up = 0.03 #Mobility (in meter-square per volt-second)
#Calculation
sig = 1/p #Conductivity (in per ohm-meter)
RH = up / sig #Hall coefficient (in cubic-meter per Coulomb)
#Result
print "Value of Hall-coefficient is ",RH," m**3/C."
```