Mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If, for an n-type semiconductor, the density of electrons is 1019 m ⁻³ and their mobility is 1.6 m2/(V.s) then the resistivity of the semiconductor (since it is an n-type semiconductor contribution of holes is ignored) is close to: (a) 2 Ω m (b) 4 Ω m (c) 0.4 Ω m (d) 0.2 Ω m

Answer: (c). For an n-type semiconductor, σ = n e μe and ρ = (1)/(n e μe). ρ = 110¹⁹ × 1.6 × 10⁻¹⁹ × 1.6 = 1/2.56 ρ ≈ 0.39 Ω m So the answer is (c) 0.4 Ω m.

Mobility of electrons in a semiconductor is defined as the ratio of… | JEE Main 2019 (9 Jan, Shift 1)

Q46JEE Main 2019 · 9 JAN · SHIFT 1Medium

Intrinsic & Extrinsic Semiconductors

Mobility of electrons in a semiconductor is defined as the ratio of their drift velocity to the applied electric field. If, for an n-type semiconductor, the density of electrons is 1019 m ${}^{-3}$ and their mobility is 1.6 m2/(V.s) then the resistivity of the semiconductor (since it is an n-type semiconductor contribution of holes is ignored) is close to:

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Answer: (c)

For an n-type semiconductor, $\sigma = n e \mu_e$ and $\rho = \dfrac{1}{n e \mu_e}$ .
$\rho = \dfrac{1}{10^{19} \times 1.6 \times 10^{-19} \times 1.6} = \dfrac{1}{2.56}$
$\rho \approx 0.39\ \Omega\,\text{m}$
So the answer is (c) $0.4\ \Omega\,\text{m}$ .

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Intrinsic & Extrinsic Semiconductors question from JEE Main 2019 (9 Jan, Shift 1)

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