Mobility of electrons in N -type Ge is 5000 cm 2 / volt sec and conductivity 5 mho / cm. If effect of holes is negligible then impurity concentration will be

Question

Mobility of electrons in N -type Ge is 5000 cm 2 / volt sec and conductivity 5 mho / cm. If effect of holes is negligible then impurity concentration will be (A) 6.25 × 1015 / cm 3 (B) 9.25 × 1014 / cm 3 (C) 6 × 1013 / cm 3 (D) 9 × 1013 / cm 3

Tardigrade Admin · Accepted Answer

σ=en e μ e ⇒ ne=(σ/e μe) =(5/1.6 × 10-19 × 5000) =6.25 × 1015 / cm 3

Q. Mobility of electrons in $N$ -type $G e$ is $5000 c m^{2}$ / volt sec and conductivity $5 mh o / c m$ . If effect of holes is negligible then impurity concentration will be

$6.25 \times 1 0^{15} / c m^{3}$

$9.25 \times 1 0^{14} / c m^{3}$

$6 \times 1 0^{13} / c m^{3}$

$9 \times 1 0^{13} / c m^{3}$

$σ = e n_{e} μ_{e}$
$\Rightarrow n_{e} = \frac{σ}{e μ _{e}}$
$= \frac{5}{1.6 \times 1 0 ^{- 19} \times 5000}$
$= 6.25 \times 1 0^{15} / c m^{3}$

Q. Mobility of electrons in N -type Ge is 5000cm2 / volt sec and conductivity 5mho/cm. If effect of holes is negligible then impurity concentration will be

6.25×1015/cm3

9.25×1014/cm3

6×1013/cm3

9×1013/cm3