Buller, Saskia, Koch, Christine, Bensch, Wolfgang, Zalden, Peter, Sittner, Roland, Kremers, Stephan, Wuttig, Matthias, Schürmann, Ulrich, Kienle, Lorenz, Leichtweiß, Thomas, Janek, Jürgen and Schönborn, Boyke (2012) Influence of Partial Substitution of Te by Se and Ge by Sn on the Properties of the Blu-ray Phase-Change Material Ge8Sb2Te11. Chemistry of Materials, 24 (18). pp. 3582-3590. DOI 10.1021/cm301809g.

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Abstract

The opto-electronic properties of the Blu-ray phase-change material Ge8Sb2Te11 were investigated and compared to partially substituted compounds. Investigations were performed on Ge8Sb2Te6Se5 (I) and SnGe7Sb2Te7Se4 (II). To monitor the influence of substitution on both cation and anion sites onto the properties, in Ge8Sb2Te6Se5, only Te was substituted by Se, while in SnGe7Sb2Te7Se4, Ge also was partially replaced by Sn, yielding an equivalent degree of substitution. The crystallization of the amorphous compound to a rhombohedral phase was observed. The first transition temperature (Tc1) is 210 °C for I and 185 °C for II, while the second transition temperature (Tc2) cannot be clearly determined, because of the coexistence of both phases. Thin-film properties were examined and an increase of density and roughness was observed for both materials upon crystallization. In situ electrical resistance measurements show a huge electrical contrast between the amorphous samples and the crystalline samples, which amounts to 4 orders of magnitude for II and 5 orders of magnitude for I. Optical properties were characterized with variable incident-angle spectroscopic ellipsometry (VASE) and Fourier Transform infrared (FTIR) spectroscopy. Substitution leads to an enormous increase of the reflectivity contrast for blue light: The reflectivity contrast between the different phases increases from 20% to 50% for I and from 20% to 74% for II.

Document Type:	Article
Research affiliation:	Kiel University Kiel University > Kiel Marine Science OceanRep > The Future Ocean - Cluster of Excellence
Refereed:	Yes
Open Access Journal?:	No
Publisher:	American Chemical Society
Projects:	Future Ocean
Date Deposited:	12 Jun 2018 10:34
Last Modified:	23 Sep 2019 21:10
URI:	https://oceanrep.geomar.de/id/eprint/43340

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