Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)

O 35.46: Poster

Tuesday, March 12, 2013, 18:15–21:45, Poster B1

Cd-content analysis of capped and uncapped CdSe quantum dots on ZnSe by Raman spectroscopy — •Utz Bass, Constantin Weiler, Jean Geurts, Alex Frey, Suddhasatta Mahapatra, and Karl Brunner — Universität Würzburg, Physikalisches Institut, Am Hubland, 97074 Würzburg

Quantum Dots (QD) offer the intriguing opportunity to study fundamental low-dimensional physics and are simultaneously employed in optoelectronic applications. Wide band gap II-VI semiconductor QD are promising candidates to extend the applications to the visible energy regime. The self-assembly of the CdSe/ZnSe QD system is driven by the large lattice mismatch. The strain relaxation mechanism consists of dot formation together with intermixing of Cd and Zn. In this study we focus on the Cd-content analysis of CdSe QDs embedded in or on top of ZnSe. CdSe QD sample series with different nominal CdSe thickness values from various MBE growth procedures are investigated by Raman spectroscopy (RS), accompanied by photoluminescence (PL). Also for uncapped QDs with quenched PL, RS enables the Cd-concentration analysis and thus allows the in-situ study of QDs. The comparison of the capped and uncapped QD results shows that the overgrowth of the QDs with the capping ZnSe layer induces a considerable additional intermixing. This susceptibility for intermixing during overgrowth explains, why on overgrown QDs the observed Cd-content essentially only depends on the nominal CdSe-thickness, although AFM-studies of uncapped QDs showed clear morphology differences for the different growth procedures.