Effective density of states ($N_c,N_v$)

The effective density of states of a parabolic semiconductor band is its density of states integrated against a thermal Boltzmann factor measured from its edge. For one spin-degenerate valley,These quantities have units of number per volume, unlike the energy-resolved density of states. In a nondegenerate semiconductor, $n=N_c{e}^{-(E_c-\mu )/(k_{B}T)}$ and $p=N_v{e}^{-(\mu -E_v)/(k_{B}T)}$; multiple equivalent valleys add their contributions.