Berlin 2005 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 18: Optische Spektroskopie dünner Schichten I
DS 18.5: Vortrag
Montag, 7. März 2005, 16:15–16:30, TU HS110
Raman spectroscopy of embedded semiconductor monolayers: CdSe in BeTe and ZnSe — •U. Bass1, S. Mahapatra1, T. Muck2, V. Wagner2, K. Brunner1, and J. Geurts1 — 1Physikalisches Institut der Universität Würzburg, EP III, Am Hubland, D-97074 Würzburg — 2International University Bremen, School of Engineering and Science, Campus Ring 8, D-28759 Bremen
Utilizing resonant excitation, Raman spectroscopy allows the analysis of single monolayers. In this way, resonant Raman spectroscopy gives access to surface layers as well as embedded monolayers. We apply this technique for II-VI semiconductor heterostructures: CdSe monolayers embedded either in BeTe or in ZnSe. When comparing these systems, we observe significant differences in interface abruptness, localization behavior of the monolayer vibration modes, and band structure alignment of ML and barrier material. Best interface abruptness and mode localisation occurs for CdSe/BeTe, while CdSe/ZnSe shows a considerable intermixing. Furthermore, the Raman spectra are distinctly influenced by details of the growth process, such as the atomic switching sequence at the interfaces and the temperature profile during growth. We correlate the Raman scattering efficiency with the photoluminescence spectra, originating from spatially direct transitions in CdSe/ZnSe, and from indirect ones in CdSe/BeTe.