When a small amount of impurity atoms are added to a semiconductor, then generally its resistivity (a) may increase or decrease depending upon the percentage of doping (b) increases (c) decreases (d) does not change

Answer: (c). Doping adds extra charge carriers (electrons from donors or holes from acceptors). More carriers means higher conductivity σ = e(neμe + nhμh), so resistivity ρ = 1/σ falls. So the answer is (c) decreases.

When a small amount of impurity atoms are added to a semiconductor… | MHT CET 2020 (16 Oct, Shift 1)

Q42MHT CET 2020 · 16 OCT · SHIFT 1Easy

Intrinsic & Extrinsic Semiconductors

When a small amount of impurity atoms are added to a semiconductor, then generally its resistivity

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Answer: (c)

Doping adds extra charge carriers (electrons from donors or holes from acceptors).
More carriers means higher conductivity $\sigma = e(n_e\mu_e + n_h\mu_h)$ , so resistivity $\rho = 1/\sigma$ falls.
So the answer is (c) decreases.

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