Boron atoms are added to a si film resulting in an impurity density of 4 × 1016 cm–3. (a) what is the conductivity type (n-type or p-type) of this film? (b) what are the equilibrium electron and hole densities at 300 k and 600 k? (c) why does the mobile carrier concentration increase at high temperatures? (d) where is the fermi level located if t = 600 k?