Donor type impurity is found in

When a small amount of impurity atoms are added to a semiconductor,then generally its resistivity

In an extrinsic semiconductor,the number densities of holes and electrons are ${N_p}$ and ${N_e}$ respectively. Then:

The mobility of free electrons is greater than that of free holes because

The typical ionisation energy of a donor in silicon is.....$eV$

The density of an electron-hole pair in a pure germanium is $3 \times 10^{16} \ m^{-3}$ at room temperature. On doping with aluminium,the hole density increases to $4.5 \times 10^{22} \ m^{-3}$. Now,the electron density (in $m^{-3}$) in doped germanium is: