The density of electrons and holes in a pure germanium sample at room temperature are equal and its value is 3× 1016 per m3 . On doping with Aluminium, increases to 4.5× 1022 per m3 . Then the electron density in doped germanium is k× 1010m- 3 . The value of k is:

Question

The density of electrons and holes in a pure germanium sample at room temperature are equal and its value is 3× 1016 per m3 . On doping with Aluminium, increases to 4.5× 1022 per m3 . Then the electron density in doped germanium is k× 1010m- 3 . The value of k is: (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

The electron and hole concentration in a semiconductor in thermal equilibrium is given by ne nh=ni2 ne=(ni2/nh)=((3 × 1016)2/4.5 × 1022)=2 × 1010 m -3

Q. The density of electrons and holes in a pure germanium sample at room temperature are equal and its value is 3×1016 per m3 . On doping with Aluminium, increases to 4.5×1022 per m3 . Then the electron density in doped germanium is k×1010m−3 . The value of k is:

The electron and hole concentration in a semiconductor in thermal equilibrium is given by ne​nh​=ni2​ ne​=nh​ni2​​=4.5×1022(3×1016)2​=2×1010m−3

The electron and hole concentration in a semiconductor in thermal equilibrium is given by $n_{e} n_{h} = n_{i}^{2}$
$n_{e} = \frac{n _{i}^{2}}{n _{h}} = \frac{( 3 \times 1 0 ^{16} ) ^{2}}{4.5 \times 1 0 ^{22}} = 2 \times 1 0^{10} m^{- 3}$