Two-particle energy spectrum in dense electron-hole plasmas

Two-particle (exciton) states in equilibrium electron-hole plasmas of highly excited semiconductors are determined. In the framework of the Greens function technique, an effective (two-particle) wave equation allows to account for the influence of the surrounding plasma in terms of (dynamic) single-particle self-energies, Pauli blocking factors, and a dynamic effective potential correction. This equation is solved by expansion of the wave function in terms of Coulomb eigenfunctions. No rational or pole approximation for the dielectric function is used. Exciton binding energies and their imaginary parts (damping of the states) as well as continuum edges are given for Ge and GaAs model systems.