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HL: Fachverband Halbleiterphysik

HL 51: Poster IV

HL 51.8: Poster

Donnerstag, 28. Februar 2008, 16:30–19:00, Poster D

Investigation of the optical properties of phase change alloys — •Konstantin Shportko, Stephan Kremers, Michael Woda, Wojciech Wełnic, and Matthias Wuttig — Institute of Physics (IA), RWTH University of Technology Aachen, Aachen, Germany

Phase change materials (PCM) have a unique potential as materials for an emerging non-volatile electronic memory [1]. The aim of this study is to investigate the permittivity dispersion and dispersion of refractive and extinction indexes of the certain alloys of group V and group VI elements. Reflectance spectra have been measured in the UV-VIS/IR range. The spectra have been simulated using SCOUT software. The thickness of the PCM layer has been determined independently. We have analyzed and compared the difference between the spectra of the amorphous and crystalline phases. Our experiments reveal very remarkable findings. Dispersion of the refractive and extinction indexes of both phases show pronounced contrast. The analysis of computations and experimental data reveal the correlation between local structural changes and optical properties as well as the origin of the optical contrast in these materials. The change in optical properties cannot be attributed to a smearing of transition energies as commonly assumed for amorphous semiconductors: the optical contrast between the two phases can only be explained by significant changes in the transition matrix elements [2]. [1] M. Wuttig, N. Yamada, Nature Materials 6, 824 (2007). [2] Welnic W., Botti S., Reining L., Wuttig M. Physical Review Letters 98 (23), 236403, (2007).