Unformatted text preview: applied voltage is 0.589 V (which is 23kT/q).
FIGURE 4–50 (b) Find 0and sketch the majority andThe light generates Gcurrentslectron–hole of x (distance from
minority carrier = 1015 e as a function
The x > portion is illuminated with light.
L
2 er s uniformly throughout voltage of part (a).
the junction),punder the applied biasthe bar in the region x > 0. GL is 0 for x < 0.
pairs per cm
Assume that the steadystate conditions prevail, the semiconductor is made of silicon,
Nd = 1018 cm–3, τ = 10–6 s, and T = 300 K. (a) What is the hole concentration at x = ∞ ? Explain your answer.
(b) What is the hole concentration at x = +∞ ? Explain your answer. (c) What is the minority carrier diffusion current as a function of x?
The purpose of the following questions is to show that the minority carrier drift current is
negligible.
(d) Use the results of parts (b) and (c) to find the majority carrier drift current, Jndrift. Then find
the electric field and finally the minority carrier drift current Jpdrift. Is Jpdrift<<Jpdiffusion? Draw the
Jpdrift and Jpdiffusion in the same graph.
(e) justify the assumption of dn=dp...
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 Spring '07
 ee130
 Pn junction, Condensed matter physics, diffusion equation, maximum electric field

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