Evaluation of Piezoelectric Ta 2 O 5 Thin Films Deposited on Sapphire Substrates

Self Cite

In this study, to obtain a substrate structure with a lower phase velocity, the propagation properties of a Love-type surface acoustic wave (Love SAW) on Y-X LiTaO 3 (LT) with an amorphous tantalum pentoxide (a-Ta 2 O 5 ) thin film were investigated using a simple delay line and a resonator with a wavelength λ of 8 µm. The insertion loss of a simple delay line was decreased markedly by loading with an a-Ta 2 O 5 film owing to a transformation from a leaky SAW (LSAW) to a non-leaky Love SAW. A phase velocity of 3,340 m/s, a coupling factor of 5.8%, and a propagation loss of 0.03 dB/λ were obtained for a normalized thickness h/λ of 0.120. Moreover, the resonance properties of the Love SAW were almost equal or superior to those for an LSAW on Al/36°Y-X LT, except for the fractional bandwidth.

Section: Sample Fabricationsupporting

confidence: 76%

Love-type surface acoustic wave onY–XLiTaO₃with amorphous Ta₂O₅thin film

Kakio

Fukasawa

Hosaka

2015

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“…A similar tendency was observed in a piezoelectric Ta 2 O 5 film deposited by the RF magnetron sputtering method on a support substrate. 47) Second, although a large variation of K 2 was observed on the same sample as described above, K 2 for the 1st mode of the STO(110) sample tends to be larger than that of the STO(100) sample. This may be due to the {110} c -oriented KNN epitaxial film having higher piezoelectricity than the {100} c -oriented KNN epitaxial film because the {110} c orientation corresponds to the c-axis orientation in the orthorhombic structure.…”

Section: Evaluation Of Saw Propertiessupporting

confidence: 51%

Evaluation of bulk and surface acoustic waves propagation properties of (K,Na)NbO₃ films deposited by hydrothermal synthesis or RF magnetron sputtering methods

Yoshizawa

Suzuki

Kakio

et al. 2022

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In this study, the bulk and surface acoustic waves (BAW and SAW) propagation properties of (K,Na)NbO3 (KNN) films deposited by hydrothermal synthesis or RF magnetron sputtering methods were evaluated to investigate the applicability of such films to high-frequency devices. For the KNN(001)-oriented films deposited by hydrothermal synthesis method, a BAW phase velocity of 6,900 m/s and an electromechanical coupling coefficient k t 2 of 8.4% were obtained. From the measured Rayleigh-type SAW properties, a large electromechanical coupling coefficient K 2 of 4.0% in the 1st mode was obtained in the KNN(011)-oriented films. On the other hand, for the KNN(001)-oriented films deposited by RF magnetron sputtering, a BAW phase velocity of 7,850 m/s and k t 2 of 7.4% were obtained. For the 0th mode of the Rayleigh-type SAW, a propagation loss of 0.13 dB/λ (λ: wavelength) at 440 MHz and a temperature coefficient of frequency of –42 ppm/°C were obtained.

“…Our group previously reported the fabrication of crystalline Ta 2 O 5 thin films on sapphire substrates by epitaxial growth. 27) However, the reduction in PL has not been confirmed.…”

Section: Introductionmentioning

confidence: 93%

Evaluation of piezoelectric Ta₂O₅thin films deposited on SrTiO₃substrates

Yu¹,

Kakio²

2017

Self Cite

Tantalum pentoxide (Ta2O5) piezoelectric thin films were deposited on (100) and (110) planes of strontium titanate (SrTiO3) substrates using an RF magnetron sputtering system. The crystallinity and Rayleigh-type surface acoustic wave propagation properties of the thin films were evaluated. The possibility that the Ta2O5 thin films were crystallized to orthorhombic Ta2O5 on SrTiO3 substrates by providing a buffer layer deposited without applying O2 radical power was demonstrated. From measured pole figures, it is considered that the crystalline Ta2O5/SrTiO3(100) sample has two lattice arrangements orthogonal to each other, and the crystalline Ta2O5/SrTiO3(110) sample has a single lattice arrangement. For a normalized film thickness h/λ of 0.45, the propagation loss for the deposition on SrTiO3(110) was 0.02 dB/λ, whereas that for the X-axis-oriented Ta2O5 thin film on SiO2 substrate was 0.21 dB/λ. Unfortunately, the coupling factor of the crystalline thin film was less than 0.3% for h/λ ranging from 0.29 to 0.45.