Bound exciton recombination in beryllium-doped silicon

The low-temperature photoluminescence of beryllium-doped silicon is dominated by a system with sharp no-phonon lines at approximately 1.077 eV with well resolved phonon-assisted replicas at lower energies. The temperature dependence of the relative intensities of the no-phonon lines and of the phonon-assisted structure is similar to that which has been observed for electron-hole recombination at axial isoelectronic traps in gallium phosphide. Using Zeeman spectroscopy the recombination centre in beryllium-doped silicon is shown to have (001) symmetry and is identified with beryllium substitutional-interstitial pairs which are expected to predominate in this material. A weak acceptor-like bound exciton spectrum is also reported.