The transition between free excitons and an electron-hole plasma is described for the first time by a theory based on full random-phase-approximation (RPA) screening in the plasma. The onset of exciton binding predicted is in excellent agreement with experimental data attributed to exciton dissociation in Si. It is suggested that the many-body electron-hole interaction may be well described by static RPA screening near the Mott transition.

• Received 10 June 1982

DOI:https://doi.org/10.1103/PhysRevB.26.6706