The donor concentration in a silicon sample at 300K is ND = 1.2 x 1015 cm-3. 1 x 1016 cm-3 acceptor atoms are added to form a compensated p-type semiconductor so that the Fermi level is 0.26 eV above the valence band edge. (a) Determine free electron and hole concentration.(b) Calculate the effective density of states at valence band, Nv. Given that ni = 1x1010 cm3 and kT = 0.026.