Chapter7:TRANSFERRED ELECTRON DEVICES(TEDs)

Eg7.2.1:pg-294

In [1]:
#Calculate the conductivity of the diode
e=1.6*(10**-19)      #charge of electron in C
nl=(10**10)*(10**6)  #electron density at lower valley in /m**3
nu=(10**8)*(10**6)   #electron density at upper valley in /m**3
ul=8000*(10**-4)     #electron mobility at lower valley in m2/V-sec
uu=180*(10**-4)      #electron mobility at upper valley in m2/V-sec
o=e*((nl*ul)+(nu*uu)) 
o=o*1000             #in milli mhos
print"The conductivity of the diode(in mmhos)is=",round(o,2),"mmhos" 

the conductivity of the diode(in mmhos)is= 1.28 mmhos

Eg7.2.2:pg-298

In [3]:
#(a)Calculate the electron drift velocity
q=1.6*(10**-19) #charge of electron in C
f=10*(10**9)    #operating frequency in Hertz
L=10*(10**-6)   #Device Length in meter
vd=f*L 
print"The electron drift velocity is =","{:.0e}".format(vd),"m/s","{:.0e}".format(vd*100),"cm/s"

#(b)Calculate the current density
n=2*(10**14)*(10**6) 
J=q*n*vd 
print"The current density is =","{:.1e}".format(J),"A/m2 =",int(round(J/(10**4))),"A/cm2"

#(c)CAPTION: Calculate the negative electron mobility
E=3200     #applied field
vd=vd*(100) #in cm/sec
un=-1*vd/E 
print"Negative electron mobility(in cm**2/V*sec) is =",int(round(un)),"cm2/V.s" #answer is wrong in book  

The electron drift velocity is = 1e+05 m/s 1e+07 cm/s
The current density is = 3.2e+06 A/m2 = 320 A/cm2
Negative electron mobility(in cm**2/V*sec) is = -3125 cm2/V.s

Eg7.3.1:pg-304

In [4]:
#Determine the criteria for classifying the modes of operation
er=13.1          #relative dielectric constant
vd=2.5*(10**5)   #electron drift velocity in m/sec
e=1.6*(10**-19)  #charge of electron in C
E=8.854*(10**-12)*er  #permittivity of GaAs in F/m
un=-0.015      #negative electron mobility in m**2/v.s
un=-1*un
a=(E*vd)/(e*un)
print"The criteria is=","{:.3e}".format(a),"/m2 =","{:.3e}".format(a/10000),"/cm2"  #calculation mistake in book    
print"This means that the product of doping concentration and the device length must be"
print"noL >","{:.3e}".format(a/10000),"/cm2"

The criteria is= 1.208e+16 /m2 = 1.208e+12 /cm2
This means that the product of doping concentration and the device length must be
noL > 1.208e+12 /cm2

Eg7.4.1:pg-311

In [5]:
#Calculate the output power
n=0.06           #conversion efficiency
M=3.5            #Multiplication factor
Eth=320*(10**3)  #threshold field in V/m
L=12*(10**-6)    #Device Length in m
n0=10**21        #Donor concentration in m**3
e=1.6*(10**-19)  #charge of electron in C
v0=1.5*(10**5)   #Average carrier velocity in m/sec
A=3*(10**-8)     #Area m**2
p=n*(M*Eth*L)*(n0*e*v0*A) 
p=p*1000         # in mW
print"The output power(in mW)is=",int(round(p)),"mW" 

The output power(in mW)is= 581 mW