Influence of Partial Substitution of Te by Se and Ge by Sn on the Properties of the Blu-ray Phase-Change Material Ge8Sb2Te11

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• 作者：Saskia Buller ; Christine Koch ; Wolfgang Bensch ; Peter Zalden ; Roland Sittner ; Stephan Kremers ; Matthias Wuttig ; Ulrich Sch眉rmann ; Lorenz Kienle ; Thomas Leichtwei脽 ; J眉rgen Janek ; Boyke Sch枚nborn
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：September 25, 2012
• 年：2012
• 卷：24
• 期：18
• 页码：3582-3590
• 全文大小：569K
• 年卷期：v.24,no.18(September 25, 2012)
• ISSN：1520-5002

文摘

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 (T_c1) is 210 掳C for I and 185 掳C for II, while the second transition temperature (T_c2) 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.

Keywords:

phase-change materials; blu-ray; optical contrast; electrical conductivity; structure; thin films