GATE EC 2021 Set 1 — Question 16
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Electronic Devices → Carrier Transport → Generation & Recombination
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Question
A bar of silicon is doped with boron concentration of and assumed to be fully ionized. It is exposed to light such that electron-hole pairs are generated throughout the volume of the bar at the rate of . If the recombination lifetime is , intrinsic carrier concentration of silicon is and assuming ionization of boron, then the approximate product of steady-state electron and hole concentrations due to this light exposure is
Correct answer
(D) 2 × 10³² cm⁻⁶
Solution
Given:
Boron concentration (p-type).
Intrinsic concentration .
Equilibrium concentrations: , .Generation rate .
Recombination lifetime .
Steady-state excess carrier concentration: .Total steady-state concentrations:
.
.The product .
Boron concentration (p-type).
Intrinsic concentration .
Equilibrium concentrations: , .Generation rate .
Recombination lifetime .
Steady-state excess carrier concentration: .Total steady-state concentrations:
.
.The product .
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