The Bohr radius of the fifth electron of phosphorus (atomic number $Z = 15$) acting as a dopant in silicon (relative dielectric constant $\varepsilon_r = 12$) is ....... $\mathring{A}$.

An $n$-type and $p$-type semiconductor can be obtained by respectively doping pure silicon with

Pure $Si$ at $500\, K$ has equal number of electron $(n_e)$ and hole $(n_h)$ concentrations of $1.5 \times 10^{16}\, m^{-3}$. Doping by indium increases $n_h$ to $4.5 \times 10^{22}\, m^{-3}$. The doped semiconductor is of

When the conductivity of a semiconductor is only due to breaking of covalent bonds, the semiconductor is called

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

In pure silicon,the electron-hole concentration at $T = 300 \ K$ is $7 \times 10^{15} \ m^{-3}$. Antimony is added as an impurity to silicon at a rate of $1$ atom per $10^7 \ Si$ atoms. Assume that half of the impurity atoms contribute their electrons to the conduction band. Calculate the factor by which the number of charge carriers increases. Given: the number density of silicon atoms is $5 \times 10^{28} \ m^{-3}$.