# Carrier Life Time MCQ’s

This set of Electronic Devices & Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Carrier Life Time”.

1. What is the process number of Schokley-Read-Hall Theory processes?
Process-‘ The capture of an electron from the conduction band by an initially neutral empty trap’
a) Process1
b) Process2
c) Process3
d) Process4

2. Calculate the recombination rate if the excess carrier concentration is 1014cm-3 and the carrier lifetime is 1µseconds.
a) 108
b) 1010
c) 1020
d) 1014

3. What is the range of the carrier lifetime?
a) Nanoseconds to microseconds
b) Nanoseconds to hundreds of microseconds
c) Nanoseconds to tens of microseconds
d) Nanoseconds to milliseconds

4. Calculate the capture rate where Cn=10, Nt=1010cm-3, n=1020 and fF (Et)=0.4.
a) 6*1030
b) 5*1030
c) 36*1030
d) 1.66*1029

5. At what condition, the rate of electron capture from the conduction band and the rate of the electron emission back into the conduction band must be equal?
a) Thermal equilibrium
b) At room temperature
c) T=250K
d) At boiling temperature

6. The number of majority carriers that are available for recombining with excess minority carriers decreases as the excess semiconductor becomes intrinsic. Is it true?
a) True
b) False

7. Calculate the emission rate where En=2.5, Nt=1010cm-3 and fF (Et)=0.6 .
a) 15*1010
b) 1.5*1010
c) 15*1011
d) 1.5*1011

8. Calculate the carrier lifetime when Cp=5 and Nt=1010cm-3.
a) 2*1011
b) 2*10-11
c) 20*10-11
d) 20*1011

9. Which of the following is used as the recombination agent by semiconductor device manufactures?
a) Silver
b) Gold
c) Platinum
d) Aluminium

10. The rate of change of the excess density is proportional to the density. Is it true of false?
a) True
b) False