Sharp-Line Photoluminescence in ZnSiP2

We have studied the photoluminescence spectra of ZnSi${\mathrm{P}}_2$. Time-resolved spectra, time decays of different spectral components, and excitation-intensity dependence studies were performed at various temperatures between 1.8 and 250°K. We observe a series of sharp emission lines (half-width ∼ 1 meV) which we attribute to phonon-assisted processes of an unidentified transition involving impurities or defects. Superimposed on this series is a featureless broad emission band. At energies above this series of lines, several other independent sharp lines are observed. Some of the latter are strongly enhanced as the temperature increases from 1.8 to 35°K. These results are discussed and compared with somewhat similar spectra of GaP.