Steady-state photoluminescence of the P-rich phosphorus selenide glasses

The continuous-wave photoluminescence (CW PL) spectra of a-P _xSe_1-x glasses of compositions x=0.66, 0.75, 0.8, and 0.84 have been investigated for a wide range of excitation energies and intensities. It is found that the Gaussian mid-gap spectra typical of glassy chalcogenides broaden dramatically for excitation energies of 2.4 eV and above. This is shown to be due to the presence of a higher-energy PL band, which is excited most efficiently at high excitation energies. This band is weaker, but still detectable, at low excitation energies for the composition a-P₃Se, x=0.75, and is then clearly resolved from the mid-gap band. The high-energy band is identified with a luminescence process with a wide range of lifetimes, whose excitation spectrum is found to be sharply peaked at an energy dependent on the composition. Results of PL studies of crystalline P₄Se₃ are also described. It is found that the high-energy band is very much weaker in the crystal, if at all present.