Tunable Microwave Filters Using HfO<sub>2</sub>-Based Ferroelectrics
In this paper, we present microwave filters that are based on 6-nm-thick ferroelectric thin films of hafnium oxide doped with zirconium (HfZrO), which are tunable continuously in targeted bands of interest within the frequency range 0.1–16 GHz, when the applied direct current (DC) voltage is swept b...
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MDPI AG
2020-10-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/10/10/2057 |
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| author | Martino Aldrigo Mircea Dragoman Sergiu Iordanescu Florin Nastase Silviu Vulpe |
| author_facet | Martino Aldrigo Mircea Dragoman Sergiu Iordanescu Florin Nastase Silviu Vulpe |
| author_sort | Martino Aldrigo |
| collection | DOAJ |
| description | In this paper, we present microwave filters that are based on 6-nm-thick ferroelectric thin films of hafnium oxide doped with zirconium (HfZrO), which are tunable continuously in targeted bands of interest within the frequency range 0.1–16 GHz, when the applied direct current (DC) voltage is swept between 0 V and 4 V. Here, we exploit the orthorhombic polar phase in HfO<sub>2</sub> through a careful doping using zirconium in an Atomic Layer Deposition (ALD) process, in order to guarantee phase stabilization at room temperature. Polarization versus voltage characterization has been carried out, showing a remanent polarization (<i>P<sub>r</sub></i>) of ~0.8 μC/cm<sup>2</sup> and the coercive voltage at ~2.6 V. The average roughness has been found to be 0.2 nm for HfZrO films with a thickness of 6 nm. The uniform topography, without holes, and the low surface roughness demonstrate that the composition and the structure of the film are relatively constant in volume. Three filter configurations (low-pass, high-pass, and band-pass) have been designed, modelled, fabricated, and fully characterized in microwaves, showing a frequency shift of the minimum of the reflection coefficient between 90 MHz and 4.4 GHz, with a minimum insertion loss of approximately 6.9 dB in high-pass configuration. |
| first_indexed | 2024-03-10T15:31:55Z |
| format | Article |
| id | doaj.art-d89c2778e3f54e7d84bd8d6a373839c6 |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-10T15:31:55Z |
| publishDate | 2020-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-d89c2778e3f54e7d84bd8d6a373839c62023-11-20T17:34:20ZengMDPI AGNanomaterials2079-49912020-10-011010205710.3390/nano10102057Tunable Microwave Filters Using HfO<sub>2</sub>-Based FerroelectricsMartino Aldrigo0Mircea Dragoman1Sergiu Iordanescu2Florin Nastase3Silviu Vulpe4National Institute for Research and Development in Microtechnologies (IMT Bucharest), Erou Iancu Nicolae Street 126A, 077190 Voluntari, Ilfov, RomaniaNational Institute for Research and Development in Microtechnologies (IMT Bucharest), Erou Iancu Nicolae Street 126A, 077190 Voluntari, Ilfov, RomaniaNational Institute for Research and Development in Microtechnologies (IMT Bucharest), Erou Iancu Nicolae Street 126A, 077190 Voluntari, Ilfov, RomaniaNational Institute for Research and Development in Microtechnologies (IMT Bucharest), Erou Iancu Nicolae Street 126A, 077190 Voluntari, Ilfov, RomaniaNational Institute for Research and Development in Microtechnologies (IMT Bucharest), Erou Iancu Nicolae Street 126A, 077190 Voluntari, Ilfov, RomaniaIn this paper, we present microwave filters that are based on 6-nm-thick ferroelectric thin films of hafnium oxide doped with zirconium (HfZrO), which are tunable continuously in targeted bands of interest within the frequency range 0.1–16 GHz, when the applied direct current (DC) voltage is swept between 0 V and 4 V. Here, we exploit the orthorhombic polar phase in HfO<sub>2</sub> through a careful doping using zirconium in an Atomic Layer Deposition (ALD) process, in order to guarantee phase stabilization at room temperature. Polarization versus voltage characterization has been carried out, showing a remanent polarization (<i>P<sub>r</sub></i>) of ~0.8 μC/cm<sup>2</sup> and the coercive voltage at ~2.6 V. The average roughness has been found to be 0.2 nm for HfZrO films with a thickness of 6 nm. The uniform topography, without holes, and the low surface roughness demonstrate that the composition and the structure of the film are relatively constant in volume. Three filter configurations (low-pass, high-pass, and band-pass) have been designed, modelled, fabricated, and fully characterized in microwaves, showing a frequency shift of the minimum of the reflection coefficient between 90 MHz and 4.4 GHz, with a minimum insertion loss of approximately 6.9 dB in high-pass configuration.https://www.mdpi.com/2079-4991/10/10/2057microwavestunable filterhafnium oxideferroelectric material |
| spellingShingle | Martino Aldrigo Mircea Dragoman Sergiu Iordanescu Florin Nastase Silviu Vulpe Tunable Microwave Filters Using HfO<sub>2</sub>-Based Ferroelectrics Nanomaterials microwaves tunable filter hafnium oxide ferroelectric material |
| title | Tunable Microwave Filters Using HfO<sub>2</sub>-Based Ferroelectrics |
| title_full | Tunable Microwave Filters Using HfO<sub>2</sub>-Based Ferroelectrics |
| title_fullStr | Tunable Microwave Filters Using HfO<sub>2</sub>-Based Ferroelectrics |
| title_full_unstemmed | Tunable Microwave Filters Using HfO<sub>2</sub>-Based Ferroelectrics |
| title_short | Tunable Microwave Filters Using HfO<sub>2</sub>-Based Ferroelectrics |
| title_sort | tunable microwave filters using hfo sub 2 sub based ferroelectrics |
| topic | microwaves tunable filter hafnium oxide ferroelectric material |
| url | https://www.mdpi.com/2079-4991/10/10/2057 |
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