Chemical Potential μ in Solids

[QuarkDecay]

TL;DR

The equation for chemical potential in solids and what each part means.

There is the equation:

μ= E_u +E_g/2 +3/4k_βTln(m_u/m_c)

Eg is the band gap, but I don't understand what E_u stands for and how we can calculate it? Could it be the valence band?

 

[Lord Jestocost]

$\mu$ is the chemical potential of electrons in a semiconductor.
$E_u$ is the energy at the top of the valence band.