An N-type sample of silicon has uniform density (Na = 101%cm) of arsenic, and a P-type silicon sample has a uniform density (Na = 1015 /cm) of boron. For each sample, determine the following: (a) The temperature at which the intrinsic concentration n exceeds the impurity density by factor of 10. (b) The equilibrium minority-carrier concentrations at 300 K. Assume full ionization of impurities. (c) The Fermi level relative to the valence-band edge E, in each material at 300 K. (d) The electron and hole concentrations and the Fermi level if both types of impurities are present in the same sample.