Theory of the electron-hole plasma in highly excited Si and Ge

Abstract

In a microscopic-model calculation the electron-hole system is treated as an interacting free-carrier system in thermal equilibrium with a nonideal exciton gas. Renormalization of the excitons is approximately taken into account. The chemical potential as a function of the total electron-hole density is discussed with respect to possible unstable regions also in the low-density regime. Making simplifying assumptions, the phase diagram for the metallic condensation is derived for Ge and Si and compared to experimental data.