Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 51: Poster IV

HL 51.16: Poster

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

Investigating transport properties of crystalline chalcogenide phase change alloys — •Stephan Kremers, Kostiantyn Shportko, Michael Woda, and Matthias Wuttig — I. Physikalisches Institut (IA), RWTH Aachen, Deutschland

Many chalcogenide alloys show a pronounced optical and electrical contrast between the amorphous and crystalline phase. The origin can be understood refer to W. Welnic (2007). Within this class of materials, phase change alloys stand out by their ability to rapidly and reversibly switch between these two metastable states. Rewritable CDs / DVDs are already taking advantage of these properties and the Phase-Change-Random-Access-Memory (PRAM) is going to enter the market, substituting flash memory in the near future.

We present Ellipsometry measurements of optical properties in the range of 0.7-3.0 eV for chalcogenide alloys. Two mechanisms dominate an optical spectra: interband transitions and free carriers. The focus of our investigations is on the free carriers which can be decribed by Drude's theory. In principle the resistivity, carrier concentration and mobility can be deduced. We show the opportunities and limits of optical techniques regarding transport phenomena.