208 CHAPTER 4. JUNCTIONS IN SEMICONDUCTORS:P-NDIODES
1.0μs; (b) 10.0 ns; and (c) 1.0 ns. Use the following parameters:
A =10−^3 cm^2
Na = Nd=10^18 cm−^3
τn = τp=10−^7 s
Dn =25cm^2 /s
Dp =6cm^2 /s
Problem 4.22Consider a GaAsp-ndiode withNa=10^17 cm−^3 ,Nd=10^17 cm−^3 .The
diode area is 10 −^3 cm^2 and the minority carrier mobilities are (at 300 K)
μn= 3000cm^2 /V·s;μp= 200cm^2 /V·s. The electron-hole recombination times are
10 −^8 s(τp=τn=τ). Calculate the diode current at a reverse bias of 5 V. Plot the diode
forward-bias current including generation-recombination current between 0.1 V and 1.0 V.
Problem 4.23A long base GaAs abruptp-njunction diode has an area of 10 −^3 cm^2 ,
Na=10^18 cm−^3 ,Nd=10^17 cm−^3 ,τp=τn=10−^8 s,Dp=6cm^2 s−^1 and
Dn= 100cm^2 s−^1. Calculate the 300 K diode current at a forward bias of 0.3 V and a
reverse bias of 5 V. The electron-hole recombination time in the depletion regions is 10 −^7 s.
Problem 4.24Two different processes are used to fabricate a Sip-ndiode. The first
process results in a electron-hole recombination time via impurities in the depletion region
of 10−^7 s while the second one gives a time of 10−^9 s. Calculate the diode ideality factors
for the two cases near a forward bias of 0.9 V. Use the following parameters:
Na = Nd=10^18 cm−^3
τn = τp=10−^7 s
Dn =25cm^2 /s
Dp =8cm^2 /s
Problem 4.25Consider a Si diode with the following parameters:
A =10−^3 cm^2
Na = Nd=10^18 cm−^3
τn = τp=10−^7 s
Dn =25cm^2 /s
Dp =8cm^2 /s
The length of then-andp-sides are 1.0μm each and the electron-hole impurity-assisted
recombination time in the depletion region is 10−^8 s. Plot the I-V relation of the diode
from−5.0 V to 1.0 V. Compare the results for the case where a long diode is made from
the same material technology.
