Pure silicon at room temperature has an electron number density in the conduction band of about 5 × 1015 m−3 and an equal density of holes in the valence band. There are about 5 × 1028silicon atoms per m3. Suppose that one of every 107 silicon atoms is replaced by a phosphorus atom. (a) Which type will the doped semiconductor be, n or p? (b) What charge carrier number density will the phosphorus add? (c) What is the ratio of the charge carrier number density (either electrons in the conduction band or holes in the valence band) in the doped silicon to that in pure silicon?

Pure silicon at room temperature has an electron number density in the conduction band of about 5 × 1015 m−3 and an equal density of holes in the valence band. There are about 5 × 1028silicon atoms per m3. Suppose that one of every 107 silicon atoms is replaced by a phosphorus atom. (a) Which type will the doped semiconductor be, n or p? (b) What charge carrier number density will the phosphorus add? (c) What is the ratio of the charge carrier number density (either electrons in the conduction band or holes in the valence band) in the doped silicon to that in pure silicon?