Dependence of the Peak Energy of the Pair-Photoluminescence Band on Excitation Intensity

Abstract

An analytical expression is derived for the dependence of the peak energy of the broad-band pair-recombination emission on the excitation intensity. Experimental values given in the literature were fitted by a nonlinear-least-square computer program to the theoretical expression. The fit gave values for the limiting photon energy for distant pairs ($h{\ensuremath{\nu}}_{\ensuremath{\infty}}$) and for the Bohr radius (${R}_{B}$) for the shallow hydrogenic impurity in the crystal. Values obtained for GaP were $h{\ensuremath{\nu}}_{\ensuremath{\infty}}=2.189$ eV and ${R}_{B}=24.2$ \AA{} (averages from two sets of experimental results). For ZnSe we obtained $h{\ensuremath{\nu}}_{\ensuremath{\infty}}=2.691$ eV and ${R}_{B}=28.1$ \AA{}. The present method is specifically useful in crystals in which the discrete-line pair emission is not observable. It can, however, also help as a guide and a check in the classification of the discrete lines according to their shell number.