Si Doped Hafnium Oxide—A “Fragile” Ferroelectric System

Claudia Richter, Tony Schenk, Min Hyuk Park, Franziska A. Tscharntke, Everett D. Grimley, James M. LeBeau, Chuanzhen Zhou, Chris M. Fancher, Jacob L. Jones, Thomas Mikolajick, Uwe Schroeder

Research output: Contribution to journalArticlepeer-review

150 Scopus citations

Abstract

Silicon doped hafnium oxide was the material used in the original report of ferroelectricity in hafnia in 2011. Since then, it has been subject of many further publications including the demonstration of the world's first ferroelectric field-effect transistor in the state-of-the-art 28 nm technology. Though many studies are conducted with a strong focus on application in memory devices, a comprehensive study on structural stability in these films remains to be seen. In this work, a film thickness of about 36 nm, instead of the 10 nm used in most previous studies, is utilized to carefully probe how the concentration range impacts the evolution of phases, the dopant distribution, the field cycling effects, and their interplay in the macroscopic ferroelectric response of the films. Si:HfO2 appears to be a rather fragile system: different phases seem close in energy and the system is thus rich in competing phenomena. Nonetheless, it offers ferroelectricity or field-induced ferroelectricity for elevated annealing conditions up to 1000 °C. Similar to the measures taken for conventional ferroelectrics such as lead zirconate titanate, engineering efforts to guarantee stable interfaces and stoichiometry are mandatory to achieve stable performance in applications such as ferroelectric memories, supercapacitors, or energy harvesting devices.

Original languageEnglish
Article number1700131
JournalAdvanced Electronic Materials
Volume3
Issue number10
DOIs
StatePublished - Oct 2017
Externally publishedYes

Funding

The authors gratefully acknowledge funding from the Army Research Office (contract number W911NF-15-1-0593). T.S. gratefully acknowledges the German Research Foundation (Deutsche Forschungsgemeinschaft) for funding part of this research in the frame of the “Inferox” project (MI 1247/11-2). M.H.P. was supported by the Humboldt postdoctoral fellowship from the Alexander von Humboldt Foundation. M.H.P. acknowledges the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2016R1A6A3A03012208). E.D.G. and J.M.L. gratefully acknowledge funding from the National Science Foundation (Award No. DMR-1350273). E.D.G. acknowledges support for this work through a National Science Foundation Graduate Research Fellowship (Grant DGE-1252376). Tina Sturm and Almut Pöhl from Leibniz IFW Dresden, Germany are acknowledged for FIB( focused ion beam) preparation of the lamellas. This work was performed in part at the Analytical Instrumentation Facility (AIF) at the North Carolina State University, which was supported by the State of North Carolina and the National Science Foundation (Award number ECCS-1542015). The AIF is a member of the North Carolina Research Triangle Nanotechnology Network (RTNN), a site in the National Nanotechnology Coordinated Infrastructure (NNCI).

Keywords

  • Landau theory
  • Rietveld analysis
  • ferroelectrics
  • hafnium oxide

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