Density functional study of the TiN/Ge2Sb2Te5 interface

Authors

  • D. Mandelli,

    1. Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 53, 20125 Milano, Italy
    2. Present address: Sissa, Trieste, Italy
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  • S. Caravati,

    1. Department of Chemistry and Applied Biosciences, ETH Zurich, and Facoltà di Informatica, Istituto di Scienze Computazionali, Università della Svizzera Italiana, Via Giuseppe Buffi 13, 6900 Lugano, Switzerland
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  • M. Bernasconi

    Corresponding author
    1. Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 53, 20125 Milano, Italy
    • Phone: +390264485231, Fax: +390264485400
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Abstract

We studied the epitaxial TiN(001)/Ge2Sb2Te5(001) (GST) interface of interest for applications in phase change non-volatile memories by means of density functional calculations. The cubic phase of GST of interest for the memory devices was considered. From geometry optimization we found an equilibrium distance of about 3.0 Å between Ti and Te, Ge and Sb atoms located directly above along the [001] direction. The interface formation energy of a large 1440-atom model is γint = 50 meV/Å2. The surface energy of TiN(001) and GST(001) are γS = 81 and 10 meV/Å2 resulting in an adhesion energy of γad = 41 meV/Å2. A good adhesion between the two materials can thus be achieved in the ideal epitaxial configuration. The presence of metal induced gap states (MIGS) is revealed by the analysis of Kohn–Sham (KS) orbitals.

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