Verified Solution • 2025–26 Session moderate

QJEEM19Ph8766: JEE Main 2019 Physics - Class 12 JEEM19Ph8766 Solution: Mobility of electrons in a semiconductor is defined as 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 contribution of holes is ignored) is close to :

Multiple Choice Options

  • A 2 Ω2\,\Omega m
  • B 4  Ω\,\Omega m
  • C 0.4  Ω\,\Omega m
  • D 0.2  Ω\,\Omega m

Step-by-Step Verified Solution

For semiconductor,

Conductivity, σ\sigma = ne q μ\mu e + nh q μ\mu h

given that semiconductor is n-type. So contribution of holes is ignored.

∴\therefore    nh q μ\mu h = 0

∴\therefore     σ\sigma = ne q μ\mu e

Resistivity, ρ\rho = 1σ{1 \over \sigma }

= 1neqμe{1 \over {{n_e}q{\mu _e}}}

= 11019×1.6×10−19×1.6{1 \over {{{10}^{19}} \times 1.6 \times {{10}^{ - 19}} \times 1.6}}

= 11.6×1.6{1 \over {1.6 \times 1.6}}

= 0.4 Ω\Omega m

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