High-density effects, stimulated emission, and electrooptical properties of ZnCdSe/ZnSe single quantum wells and laser diodes

In II-VI material based laser diode structures, the role of excitonic processes for stimulated emission is still rather controversially discussed. In this paper, the manifestation of biexciton recombination in high-density luminescence of ZnCdSe/ZnSe quantum wells is investigated by intensity- and polarization-dependent spectroscopy. In spite of their evidence in such spectra, their contribution to stimulated emission in laser diodes with moderately confining wells is not confirmed, instead, indication of strong Coulomb correlation is given when using the new technique of pump-and-probe excitation spectroscopy. A strong electrooptic effect yielding saturation is found in laser diodes exactly at their lasing wavelength thus being promising candidates for integrated laser-modulation devices.