The GATE Grind

GATE 2014 EC (EC3) – Question 19

Electronic Devices · Carrier Transport · 1 mark · Multiple choice

A thin p-type silicon sample is uniformly illuminated, creating excess carriers. Recombination rate is directly proportional to ______.

  1. minority-carrier mobility
  2. minority-carrier recombination lifetime
  3. majority-carrier concentration
  4. excess minority-carrier concentration

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Correct answer: (D) excess minority-carrier concentration

Explanation

In the low-level injection lifetime model, the excess minority-electron recombination rate in p-type material is R=Δn/τn. With lifetime fixed, it is directly proportional to the **excess minority-carrier concentration,D**, and inversely proportional to lifetime. Mobility governs transport rather than this recombination law.