= Density-of-states effective mass
{title2=$N_c=2[m_{\mathrm{DOS}}k_BT/(2\pi\hbar^2)]^{3/2}$}
A scalar <effective mass> chosen to reproduce carrier state counting near a band edge. For $g_v$ equivalent ellipsoidal conduction valleys, $m_{\mathrm{DOS}}^{3/2}=g_v(m_lm_t^2)^{1/2}$ 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, $3/m_{\mathrm{cond}}=1/m_l+2/m_t$.
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