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ECSE-2210 Microelectronics Technology
Class Activity 17
1. What is the root cause of the delay in switching from the on-state to the off state?
2. Name the two mechanisms that act to remove the stored excess charge during the turn-off
transient.
3. An ideal p+-n diode carrying a forward current IF is suddenly reverse biased such that a
current IR flows through it at t = 0+. The storage time measured was ts. Determine what
happens to ts (increase or decrease) if:
a. Only IF is increased.
b. Only |IR| is increased.
c. The hole lifetime,
τ
p, is increased.
4. a. An ideal p+-n diode carrying a forward current IF is suddenly open circuited at
t = 0. Sketch the expected variation of pn(x, t) versus x at progressively increasing times
after open circuiting the diode.
b. Repeat the same if the diode above is reverse biased at t = 0 such that a current IR flows
through it at t = 0+.
