Draw the energy band diagram of a p-type semiconductor.

A doped semiconductor has  impurity levels $0.01 \mathrm{eV}$ above the valence band. Is it an n-type semiconductor or p-type?

The band gap between the valence and the conduction bands in Germanium is $0.7 \mathrm{eV}$. If an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in the process.

In a p-n junction, the depletion region is $2 \mathrm{\mu m}$ wide and an electric field of $1.0 \mathrm{x} {10}^5 \mathrm{v} {\mathrm{m}}^{-1}$ exists in it. Find the height of the potential barrier.