Density-of-states effective mass ($N_c=2[m_{\mathrm{DOS}}{k}_{B}T/(2\pi {\hslash }^2){]}^{3/2}$)

A scalar effective mass chosen to reproduce carrier state counting near a band edge. For $g_v$ equivalent ellipsoidal conduction valleys, $m_{\mathrm{DOS}}^{3/2}=g_v(m_l{m}_t^2{)}^{1/2}$ when the displayed factor two accounts for spin degeneracy. The valley degeneracy is then already included and must not be multiplied in again. A conductivity mass weights inverse curvatures and is generally different; for an isotropically averaged set of ellipsoids, $3/m_{\mathrm{cond}}=1/m_l+2/m_t$.