Design an ideal abrupt silicon PN-junction at 300K such that the donor impurity concentration in the n-side Nd = 5x1015/

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Design an ideal abrupt silicon PN-junction at 300K such
that the donor impurity concentration in the n-side
Nd =
5x1015/cm3 and the acceptor impurity
concentration in the p-side Na=
186x1015/cm3. Use the diode parameters: diode
area =
2x10-3cm2, ni =
1010/cm3, Dn=25
cm2/s,
Dp=10cm2/s, n
= p =
5x10-7s, r =
11.8, n =
1350 cm2/V.s, p =
450cm2/V.s.
Determine the following when a forward bias of 0.6V is
applied to the diode:
1. The contact potential Vc (in V).
2. The values (in m) of the depletion
width at the p-side xp and the depletion
width at the n-side xn.
3. The electric field (V/cm) at a distance of 0.2
x xn away from the metallurgical junction in
the n-side.
4. Minority carrier hole diffusion current in mA at the n-side
depletion edge Ip (xn)
5. Minority carrier electron diffusion current in mA at the
p-side depletion edge
In (-xP)
6. The total diode current I in mA.
7. The junction capacitance Cj in F.
Summarize your answers in a
table in your answer sheet for Q1 to Q7 as follows:
a. Contact potential
Vc (V)
b. Depletion width
xp (m)
c. Depletion width xn (m)
d. Electric field (V/cm)
e. Ip (xn) in mA
f. In (-xp) in mA
g. Diode current, I (mA)
h. Capacitance Cj
(F)
8. Roughly, sketch the
carrier distribution across the junction under forward bias. Label
clearly.
9. Calculate and prove that
the magnitude of electric field far away from the depletion region
is small compared to that in the space charge
region.
10. For the same forward bias
of 0.6V, an application requires higher diode current than that
calculated in part 6. if you have a choice to change the dopant
concentration in one side of the junction (either p-side or n-side)
to achieve this higher current, state whether you will increase or
decrease the dopant concentration in the chosen side? Briefly
explain your answer.
11. If the PN-junction diode
is made of GaAs semiconductor instead of Silicon, do you expect the
total diode current I to remain the same, decrease or increase for
the same forward bias of 0.6V? Explain briefly
without doing any calculation.