Pure silicon at 300K has electron and hole density each equal to1.5x106 m-. One of every 1.0 x107 atoms is replaced by a phosphorous atom. (a) What charge carrier density will the phosphorous add? Assume that all the donor electrons are in the conduction band. (b) Find the ratio of the charge carrier density in the doped silicon to that for the pure silicon. Given: density of silicon = 2330 kg m-; Molar mass of silicon = 28.1 g/mol; Avogadro constant NA= 6.02 x10 23 mol -.