Luminescence and Lasing in ZnSe Micropowders at High Optical Excitation Levels

Photoluminescence (PL) of ZnSe wide-bandgap semiconductor micropowder was studied at a high optical excitation level by pulsed nanosecond N-2-laser emission. A new emission band that appeared on the long-wavelength edge of the PL spectrum at 40-75 meV from the electron-hole plasma (EHP) band depending on the optical excitation level showed that plasmons could participate in recombination processes in the EHP. Random lasing at 475 nm from submicron-sized crystallites in ZnSe powder was produced by the third harmonic of a YAG:Nd3+ laser with an exciting-radiation threshold intensity of 750 kW/cm(2). The lasing manifested as a sharp increase of integrated emission intensity, a narrowing of the spectrum, and the appearance in it of localized and extended mode structure. Random lasing was due to feedback of amplified radiation in closely packed active scattering microcrystallites.