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Question:

The 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, the contribution of holes is ignored) is close to:

0.4Ωm

2Ωm

0.2Ωm

4Ωm

Solution:

The correct option is B
0.4Ωm
j = σε = nevd
σ = nevd/E = neμ
ρ = 1/σ = 1/(neμ)
ρ = 1/(1019 × 1.6 × 1.6 × 10-19) = 0.4Ωm