Dresden 2006 – scientific programme

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DF: Dielektrische Festkörper

DF 7: Dielectric and Ferroelectric Thin Films and Nanostructures II

DF 7.2: Talk

Wednesday, March 29, 2006, 14:50–15:10, K{\"O}N Farb

Charge states of native point defects in Pr-based high-k dielectrics — •Jarek Dabrowski¹, Andrzej Fleszar², Grzegorz Lupina¹, Gunther Lippert¹, Anil Mane¹, and Christian Wenger¹ — ¹IHP, Im Technologiepark 25, 15236 Frankfurt(Oder), Germany — ²Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

High-k dielectric films can trap electric charge, which aggravates their application in silicon technology as dielectrics in MOS transistors and MIM capacitors. On the basis of ab initio calculations for band offsets and defect formation energies we discuss the charge states of native point defects in Pr oxides and silicates. In particular, we find that oxygen vacancies in Pr₂O₃ introduce electron transition states at Fermi energies falling within the range of the Si substrate band gap. In thin films grown on Si, oxygen intersitials are always negatively charged in Pr₂O₃ (i.e., they act as negative fixed charges there) and always electrically neutral in PrO₂. In Pr silicates, a valence alternation defect consisting of a Si atom with a dangling bond interacting with an O atom from the silicate network is expected to be the source of a positive fixed charge.