In a $P$-type semiconductor,there is

The temperature $(T)$ dependence of resistivity $(\rho)$ of a semiconductor is represented by

In $N$-type semiconductors,the majority charge carriers are

Write briefly on $n$-type and $p$-type semiconductors.

Holes are charge carriers in

$A$ donor atom in a semiconductor has a loosely bound electron. The orbit of this electron is considerably affected by the semiconductor material but behaves in many ways like an electron orbiting a hydrogen nucleus. Given that the electron has an effective mass of $0.07 \, m_e$,where $m_e$ is the mass of the free electron,and the space in which it moves has a permittivity of $13 \, \varepsilon_0$,then the radius of the electron's lowermost energy orbit will be close to ................. $\mathring{A}$ (take the Bohr radius of the hydrogen atom as $0.53 \mathring{A}$).