First-Principles Study on Electronic Structure and Thermodynamic Stability of Sr(Ti,Ru)O_3 : Electrical Properties of Condensed Matter

概要

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Not only the electronic structure but also the thermodynamic stability of Sr(Ti,Ru)O_3 is investigated using the first-principles method. For the electronic structure with small Ru concentration, the Ru t_<2g&get states appear below the middle of the band gap of SrTiO_3. In this case, the wave functions of the Ru t_<2g&get states are localized at the Ru site. As a Ru concentration increases to more than 50 mol%, the inside-gap states gradually become delocalized. Therefore, a conductive Sr(Ti,Ru)O_3 thin film is expected. On the other hand, thermodynamic stability of a Sr(Ti,Ru)O_3 thin film is enhanced drastically relative to that of SrRuO_3, as Ru concentration decreases. Sr(Ti,Ru)O_3 with Ru concentration of more than 60 mol% may oxidize the neighboring (Ti,Al)N layer, which is often used as a barrier metal in memory-cell capacitors. In short, Sr(Ti,Ru)O_3 with Ru concentration of about 50 mol% is proposed as a promising candidate material for new electrodes.
社団法人応用物理学会の論文
2001-02-01