Luminescent properties of BexCd1-xSe thin films

We report photoluminescence (PL) study of BexCd1KxSe epitaxial layers (x!0.21) grown by molecular beam epitaxy on InP substrates. Continuous wave PL spectra are taken within a 4.2–300 K temperature range. We observe an anomalous ‘s-shaped’ temperature dependence of emission energy and a severe decrease of emission intensity with the increase of temperature. We explain an ‘s-shaped’ temperature dependence of emission energy by exciton localization in the potential minima at low temperatures followed by thermal activation at higher temperatures. We attribute low emission intensity at high temperatures to exciton dissociation and electron/hole migration to non-radiative recombination centers. q 2005 Elsevier Ltd. All rights reserved. PACS: 71.35.Cc; 71.55.Gs; 78.55.Et