Chapter 10 SILICON CONTROLLED RECTIFIER

Exmaple 10_2 pgno: 296

In [1]:
#exa 10.2
Nd =10**14
print"Nd = ",Nd," /cmˆ−3" # initializing value of donor ion concentration .
Er =11.9
print"Er = ",Er # initializing value of relative dielectric permittivity constant .
e=1.6*10**-19
print"e = ",e," columns" # initializing value of charge of electrons .
Eo=8.854*10**-14
print"Eo = ",Eo," F/cm" # initializing value of permittivity of free space .
W=100*10**-4
print"W = ",W," cm" # initializing value of width of SCR.
E=Eo*Er
print" total permittivity ,E=Eo∗Er=",E," F/cm" # calculation
Vpt=(e*Nd*W**2)/(2*E)
print"Punch trough voltage ,Vpt=(e∗Nd∗Wˆ2)/(2∗E))=",Vpt," V"# calculation
Nd =  100000000000000  /cmˆ−3
Er =  11.9
e =  1.6e-19  columns
Eo =  8.854e-14  F/cm
W =  0.01  cm
 total permittivity ,E=Eo∗Er= 1.053626e-12  F/cm
Punch trough voltage ,Vpt=(e∗Nd∗Wˆ2)/(2∗E))= 759.282705628  V

Exmaple 10_3 pgno: 296

In [1]:
#exa 10.3
Ia =2e-3
print"Ia = ",Ia," A" # initializing value of forward current of thyrsistor .
x=0.9
print"(ap+an) = ",x # initializing value of sum of current gain of n,ptype semiconductor [ value is get in by variable x,but represented on console window through ap +an ] .
a=0.45
print"a = ",a  # initializing value of current gain of both n,p type semiconductor (as it is assume that ap[current gain of n type semiconductor]=an[ current gain of ptype semiconductor ] in the question ) .
Ico=Ia*(1-(2*a))
print"Ico=Ia∗(1−(2∗an))=",Ico," A" # calculation
y=1./2.*Ico*((Ia)**-2)
print"(da/dt)=1/2∗Ico∗((Ia)ˆ−2))=",y," /A" # calculation
#The answer for (da/dt) after doing calculation is provided wrong in the book .
Ia =  0.002  A
(ap+an) =  0.9
a =  0.45
Ico=Ia∗(1−(2∗an))= 0.0002  A
(da/dt)=1/2∗Ico∗((Ia)ˆ−2))= 25.0  /A