Dynamical screening and self‐energy of excitons in the electron–hole plasma

Abstract The dependence of two‐particle energies on plasma density is investigated using Green's functions. An effective exciton equation is derived taking into account dynamically screened potential and one‐particle self‐energies. A variational calculation shows that the bound state levels (exciton energies) remain practically constant whereas the continuum edge (band gap) shifts to lower energies with increasing density, which is in accordance with experimental observations.