GATE 2014 EC (EC3) – Question 20

Electronic Devices · Carrier Transport · 1 mark · Numerical answer

At 300 K, hole mobility is 500 cm²/(V·s) and kT/q = 26 mV. Find hole diffusion constant D_p (cm²/s).

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Correct answer: 12.9 to 13.1

Explanation

Einstein’s relation connects diffusion and mobility:Dp=µp(kT/q). With µp=500cm²/(V·s) and thermal voltage26mV=0.026V, Dp=500×0.026=**13cm²/s**. The voltage units cancel when multiplying.