5 GHz laterally-excited bulk-wave resonators (XBARs) based on thin platelets of lithium niobate

In a free-standing 400-nm-thick platelet of crystalline ZY-LiNbO3, narrow electrodes (500 nm) placed periodically with a pitch of a few microns can eXcite standing shear-wave bulk acoustic resonances (XBARs), by utilising lateral electric fields oriented parallel to the crystalline Y-axis and parall...

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Bibliographic Details
Published in:Electronics letters Vol. 55; no. 2; pp. 98 - 100
Main Authors: Plessky, V, Yandrapalli, S, Turner, P.J, Villanueva, L.G, Koskela, J, Hammond, R.B
Format: Journal Article
Language:English
Published: The Institution of Engineering and Technology 24.01.2019
Subjects:
4th generation mobile phones
5th generation mobile phones
acoustic resonators
bulk acoustic wave devices
crystal resonators
crystalline Y‐axis
electrodes
free‐standing platelet
frequency 3.0 GHz to 6.0 GHz
frequency 5.0 GHz
high frequency filter
lateral electric fields
laterally‐excited bulk‐wave resonators
LiNbO3
lithium compounds
lithium niobate
low‐loss filters
MEMS process
micromechanical devices
microwave filters
microwave resonators
Microwave technology
narrow electrodes
optical photolithography
photolithography
piezoelectric coupling
quality‐factors
Q‐factor
resonance frequency
resonance Q‐factor
resonance‐antiresonance frequency spacing
RF filters
shear‐wave bulk acoustic resonances
size 400 nm
size 500.0 nm
wide band filters
XBAR
Q-factor
4th generation mobile phones
MEMS process
resonance frequency
micromechanical devices
size 500.0 nm
lithium niobate
quality-factors
low-loss filters
laterally-excited bulk-wave resonators
high frequency filter
5th generation mobile phones
bulk acoustic wave devices
frequency 5.0 GHz
crystal resonators
crystalline Y-axis
resonance-antiresonance frequency spacing
electrodes
microwave resonators
free-standing platelet
piezoelectric coupling
size 400 nm
acoustic resonators
lateral electric fields
LiNbO3
lithium compounds
resonance Q-factor
photolithography
narrow electrodes
XBAR
frequency 3.0 GHz to 6.0 GHz
wide band filters
optical photolithography
microwave filters
shear-wave bulk acoustic resonances
RF filters
ISSN:0013-5194, 1350-911X, 1350-911X
Online Access:Get full text
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Summary:In a free-standing 400-nm-thick platelet of crystalline ZY-LiNbO3, narrow electrodes (500 nm) placed periodically with a pitch of a few microns can eXcite standing shear-wave bulk acoustic resonances (XBARs), by utilising lateral electric fields oriented parallel to the crystalline Y-axis and parallel to the plane of the platelet. The resonance frequency of ∼4800 MHz is determined mainly by the platelet thickness and only weakly depends on the electrode width and the pitch. Simulations show quality-factors (Q) at resonance and anti-resonance higher than 1000. Measurements of the first fabricated devices show a resonance Q-factor ∼300, strong piezoelectric coupling ∼25%, (indicated by the large Resonance-antiResonance frequency spacing, ∼11%) and an impedance at resonance of a few ohms. The static capacitance of the devices, corresponds to the imaginary part of the impedance ∼100 Ω. This device opens the possibility for the development of low-loss, wide band, RF filters in the 3–6 GHz range for 4th and 5th generation (4G/5G) mobile phones. XBARs can be produced using standard optical photolithography and MEMS processes. The 3rd, 5th, 7th, and 9th harmonics were observed, up to 38 GHz, and are also promising for high frequency filter design.
Bibliography:S. Yandrapalli: Also with EPFL, Lausanne, Switzerland
ISSN:0013-5194
1350-911X
1350-911X
DOI:10.1049/el.2018.7297