High Dielectric Tunability and Figure of Merit at Low Voltage in (001)-Oriented Epitaxial Tetragonal Pb<sub>0.52</sub>Zr<sub>0.48</sub>TiO<sub>3</sub> Thin Films
Ferroelectric thin films with a high dielectric tunability (<i>η</i>) have great potential in electrically tunable applications, including microwave tunable devices such as phase shifters, filters, delay lines, etc. Using a modified Landau–Devonshire type thermodynamic potential, we show...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Nanomaterials |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2079-4991/15/9/695 |
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| Summary: | Ferroelectric thin films with a high dielectric tunability (<i>η</i>) have great potential in electrically tunable applications, including microwave tunable devices such as phase shifters, filters, delay lines, etc. Using a modified Landau–Devonshire type thermodynamic potential, we show that the dielectric tunability <i>η</i> of a (001) tetragonal ferroelectric film can be analytically solved. After a survey of materials, a large <i>η</i> value above 60% was predicted to be achievable in a (001)-oriented tetragonal Pb(Zr<sub>0.52</sub>Ti<sub>0.48</sub>)O<sub>3</sub> (PZT) film. Experimentally, (001)-oriented PZT thin films were prepared on LaNiO<sub>3</sub>-coated (100) SrTiO<sub>3</sub> substrates by using pulsed laser deposition (PLD). These films exhibited good dielectric tunability (<i>η</i> ~ 67.6%) measured at a small electric field <i>E</i> of ~250 kV/cm (corresponding to 5 volts for a 200 nm thick film). It only dropped down to ~54.2% when <i>E</i> was further reduced to 125 kV/cm (2.5 volts for 200 nm film). The measured dielectric tunability <i>η</i> as functions of the applied electric field <i>E</i> and measuring frequency <i>f</i> are discussed for a 500 nm thick PZT film, with the former well described by the theoretical <i>η</i>(<i>E</i>) curves and the latter showing a weak frequency dependence. These observations validate our integrated approach rooted in a theoretical understanding. |
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| ISSN: | 2079-4991 |