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Unveiling the complex electronic structure of amorphous metal oxides

Författare:
  • C. Arhammar
  • Annette Pietzsch
  • Nicolas Bock
  • Erik Holmstroem
  • C. Moyses Araujo
  • Johan Grasjo
  • Shuxi Zhao
  • Sara Green
  • T. Peery
  • Franz Hennies (Dr.)
  • Shahrad Amerioun
  • Alexander Foehlisch
  • Justine Schlappa
  • Thorsten Schmitt
  • Vladimir N. Strocov
  • Gunnar A. Niklasson
  • Duane C. Wallace
  • Jan-Erik Rubensson
  • Borje Johansson
  • Rajeev Ahuja
Publiceringsår: 2011
Språk: Engelska
Sidor: 6355-6360
Publikation/Tidskrift/Serie: Proceedings of the National Academy of Sciences
Volym: 108
Nummer: 16
Dokumenttyp: Artikel
Förlag: National Academy of Sciences of the United States of America

Sammanfattning

Amorphous materials represent a large and important emerging area of material's science. Amorphous oxides are key technological oxides in applications such as a gate dielectric in Complementary metal-oxide semiconductor devices and in Silicon-Oxide-Nitride-Oxide-Silicon and TANOS (TaN-Al2O3-Si3N4-SiO2-Silicon) flash memories. These technologies are required for the high packing density of today's integrated circuits. Therefore the investigation of defect states in these structures is crucial. In this work we present X-ray synchrotron measurements, with an energy resolution which is about 5-10 times higher than is attainable with standard spectrometers, of amorphous alumina. We demonstrate that our experimental results are in agreement with calculated spectra of amorphous alumina which we have generated by stochastic quenching. This first principles method, which we have recently developed, is found to be superior to molecular dynamics in simulating the rapid gas to solid transition that takes place as this material is deposited for thin film applications. We detect and analyze in detail states in the band gap that originate from oxygen pairs. Similar states were previously found in amorphous alumina by other spectroscopic methods and were assigned to oxygen vacancies claimed to act mutually as electron and hole traps. The oxygen pairs which we probe in this work act as hole traps only and will influence the information retention in electronic devices. In amorphous silica oxygen pairs have already been found, thus they may be a feature which is characteristic also of other amorphous metal oxides.

Disputation

Nyckelord

  • Technology and Engineering
  • stochastic quench
  • X-ray absorption spectroscopy
  • ab initio
  • coating

Övriga

Published
Yes
  • ISSN: 0027-8424

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