Binding of an exciton to a donor‐acceptor pair in a semiconductor. I. Critical binding in the case of a Coulomb interaction

It is shown that a stable binding of an electron and a hole in the finite dipole field of both an ionized donor and an ionized acceptor cannot occur, if the donor‐acceptor pair distance is smaller than a certain critical value depending on the dielectric constant ϵ and on the electron and hole effective masses m and m . Accurate upper and lower bounds of the critical distance are derived in the model defined by these physical constants, and compared to the experimental data available from the observed luminescence spectra in doped ZnSe and AlSb.