Progress and perspective on different strategies to achieve wake-up-free ferroelectric hafnia and zirconia-based thin films

• Published in: Applied materials today Vol. 26; p. 101394
• Main Authors: Silva, J.P.B., Sekhar, K.C., Negrea, R.F., MacManus-Driscoll, J.L., Pintilie, L.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2022
• Subjects: (Pseudo-)binary oxides; Epitaxial growth; Ferroelectricity; Wake-up effect; (Pseudo-)binary oxides; Ferroelectricity; Epitaxial growth; Wake-up effect
• ISSN: 2352-9407; 2352-9415
• DOI: 10.1016/j.apmt.2022.101394

•Ferroelectric binary oxides are of enormous interest for use a negative capacitance dielectrics in gate dielectrics to field-effect transistors (FETs), and in ferroelectric switching devices for non-volatile, low power memory and neuromorphic computing.•Different strategies such as microstructure tailoring, defect, bulk and interface engineering, doping, NH3 plasma treatment and epitaxial growth have been employed to obtain wake-up free orthorhombic ferroelectric hafnia and zirconia films.•Epitaxial rhombohedral hafnia/zirconia films are also being explored. The rhombohedral phases can exhibit wake-up-free ferroelectric behaviour and aids fundamental understanding of ferroelectric phenomena in this system. The studies pave the way towards exploiting ferroelectric behaviour for next-generation memory and logic gate applications.
In the last decade orthorhombic hafnia and zirconia films have attracted tremendous attention arising from the discovery of ferroelectricity at the nanoscale. However, an initial wake-up pre-cycling is usually needed to achieve a ferroelectric behaviour in these films. Recently, different strategies, such as microstructure tailoring, defect, bulk and interface engineering, doping, NH3 plasma treatment and epitaxial growth, have been employed to obtain wake-up free orthorhombic ferroelectric hafnia and zirconia films. In this work we review recent developments in obtaining polar hafnia and zirconia-based thin films without the need of any wake-up cycling. In particular, we discuss the rhombohedral phase of hafnia/ zirconia, which under a constrained environment exhibits wake-up-free ferroelectric behaviour. This phase could have a strong impact on the current investigations of ferroelectric binary oxide materials and pave the way toward exploiting ferroelectric behaviour for next-generation memory and logic gate applications.
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