Influence of the composition profile in the excitonic emission of thin graded ZnCdSe quantum wells

Abstract

AbstractWe employed submonolayer pulsed beam epitaxy (SPBE) to grow thin graded Zn1‐xCdx Se quantum wells (QW) in a layer‐by‐layer mode. The Cd content, controlled at the monolayer (ML) scale, was gradually increased towards the center of the QW in order to produce a symmetric composition profile. Three samples, each one containing a 15 ML thick graded Zn1‐xCdx Se QW, were grown. The only difference between the QWs was the composition of the central three MLs. The samples were characterized by means of photoluminescence (PL) spectroscopy. Each one presented a single excitonic peak, and large differences in the excitonic emission energy were observed, even though the QWs composition profiles were quite similar. The excitonic spectra of these samples were also compared with those of a rectangular 16 ML thick Zn1‐xCdx Se QW and a 3 ML CdSe ultra‐thin QW with emissions around the same energy. Two of the graded QWs presented intensities comparables to the rectangular QWs. These results evidence the sensitivity of the QW levels to minor modifications in their potential profile and, furthermore, confirm the capability of SPBE to modulate the Cd content of Zn1‐xCdx Se QWs at the monolayer scale. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)