#importing modules
import math
from __future__ import division
#Variable declaration
h=6.62*10**-34; #planck's constant(J sec)
c=3*10**8; #velocity of light(m/sec)
Eg=1.43*1.6*10**-19; #energy gap(J)
#Calculation
lamda=h*c*10**6/Eg; #wavelength of radiation(micro m)
#Result
print "wavelength of radiation is",round(lamda,3),"micro m"
#importing modules
import math
from __future__ import division
#Variable declaration
d=5*10**-6; #thickness(m)
Dc=3.4*10**-3; #diffusion coefficient(m**2 S-1)
#Calculation
tow_diff=d**2/(2*Dc); #time taken(s)
#Result
print "time taken is",round(tow_diff*10**9,1),"*10**-9 s"
#importing modules
import math
from __future__ import division
#Variable declaration
w=5*10**-6; #thickness(m)
vsat=10**5; #velocity(m/s)
#Calculation
tow_drift=w/vsat; #transit time(s)
#Result
print "transit time is",tow_drift,"s"
#importing modules
import math
from __future__ import division
#Variable declaration
A=10**-6; #area(m**2)
e=1.6*10**-19; #charge(coulomb)
Nd=10**21; #electron concentration(m**-3)
epsilonr=11.7;
epsilon0=8.85*10**-12;
V=10; #potential(V)
RL=50; #resistance(ohm)
#Calculation
Cj=(A/2)*math.sqrt(2*e*epsilonr*epsilon0*Nd/V); #diode capacitance(F)
delta_fel=1/(2*math.pi*RL*Cj); #frequency bandwidth(Hz)
#Result
print "diode capacitance is",round(Cj*10**12,1),"pF"
print "frequency bandwidth is",int(delta_fel*10**-6),"MHz"
print "answer varies due to rounding off errors"