Hydrostatic pressure dependence of isoelectronic bound excitons in beryllium-doped silicon

Photoluminescence (PL) from the recombination of excitons bound to isoelectronic ${\mathrm{Be}}_{2}$ dopants in bulk silicon is measured for pressures up to 60 kbar and temperatures down to 9 K. PL from excitons bound to this ${\mathrm{Be}}_{2}$ trap is analyzed by using the Hopfield-Thomas-Lynch model, extended to treat more complex isoelectronic dopants, and several different binding potentials. This modified model describes the change in exciton binding energy with pressure determined from the PL spectrum and the loss of PL at and above 60 kbar when short-range potentials are used. The depth of the potential in this model is relatively insensitive to pressure. Coulomb-based models do not explain these observations as well. \textcopyright{} 1996 The American Physical Society.