Carrier-density dependence of the photoluminescence lifetimes in ZnCdSe/ZnSSe quantum wells at room temperature

Abstract

Photoluminescence lifetimes have been measured at room temperature as a function of carrier density in ZnCdSe/ZnSSe quantum wells. We show that, at low carrier density (5 ? 109?5 ? 1010 cm ? 2), nonradiative recombination dominates, while radiative recombination becomes more dominant as the carrier density is increased from 5 ? 1010 to 5 ? 1011 cm ? 2. Above ~ 5 ? 1011 cm ? 2, band filling effects are shown to produce a saturation of the lifetimes. A simple rate equation model approach can be used to describe the carrier density dependence of the photoluminescence decay data obtained on a wide range of samples. A representative band-to-band recombination coefficient of 8 ? 10?4 cm2 s ? 1 and a Shockley?Read?Hall rate of 7.3 ? 107 s ? 1 were determined for one of the better samples studied. We believe that the excellent quality of our samples has allowed for the radiative recombination coefficient to be characterized accurately at room temperature