LiNbO 3 thin film for A 1 mode of Lamb wave resonators

et al. 2021

IEEE J. Microw.

This paper presents a short review of the microwave acoustics area, where exciting material innovations and performance advancements have been made in the past decade. The ever-growing demand for more sophisticated passive signal processing functions on-chip has fueled these developments. As a result, microwave acoustic devices have maintained performance leadership in mobile applications. By evaluating three fundamental parameters, namely electromechanical coupling (k 2 ), quality factors, and frequency scalability, of microwave acoustics, this paper aims to, extensively but not exhaustively, capture the rationales behind approaches achieving higher performance microsystems. Outlooks for different material systems and addressing their underlying challenges are also offered in hopes of establishing a balanced roadmap for future microwave acoustics development.

Section: Higher Coupling Operational Modesmentioning

confidence: 99%

Microwave Acoustic Devices: Recent Advances and Outlook

Gong

et al. 2021

IEEE J. Microw.

“…Alternatively, the first-order antisymmetric (A1) Lamb wave mode resonators based on lithium niobate (LiNbO3) thin films have recently been studied as a compelling solution for sub-6 GHz wideband filters due to their high kt 2 (>20%) and record-break FoM [9]- [12]. Despite their prospect of enabling wideband and low loss filters, the demonstrated A1 devices so far are all laden with the lateral spurious modes [13]- [17].…”

Section: Introductionmentioning

confidence: 99%

Lateral Spurious Mode Suppression in Lithium Niobate A1 Resonators

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

Gao

et al. 2021

This work presents an improved design that exploits dispersion matching to suppress the spurious modes in the lithium niobate first-order antisymmetric (A1) Lamb wave mode resonators. The dispersion matching in this work is achieved by micro-machining the lithium niobate thin film to balance the electrical and mechanical loadings of electrodes. In this article, the dispersion matchings of the A1 mode in lithium niobate based on different metals are analytically modeled and validated with finite element analysis. The fabricated devices exhibit spurious-free responses with a quality factor of 692 and an electromechanical coupling coefficient of 28%. The demonstrated method herein could overcome a significant hurdle that is currently impeding the commercialization of A1 devices.

“…T HIN-FILM lithium niobate (LiNbO 3 ) based acoustic microsystems have been extensively studied in the last decade, ranging from acoustic resonators [1]- [6], transformers [7]- [9], delay lines [10]- [14], to emerging acoustoelectric amplifiers [15], non-reciprocal networks [16], [17], acousto-optic modulators [18]- [21], and quantum systems [22]. The platform receives growing research attention because various acoustic modes with high electromechanical coupling (K 2 ) and low loss can be excited in thin-film LiNbO 3 .…”

Section: Introductionmentioning

confidence: 99%

“…As a result, it enables efficient piezoelectric transduction between the electrical and acoustic domains. These modes, e.g., fundamental symmetric (S0) [6], shear-horizontal (SH0) [2], and first-order antisymmetric (A1) [1], which could not be efficiently excited in conventional bulk LiNbO 3 substrates [23], are only made available thanks to the thin-film transfer techniques of single-crystal LiNbO 3 [24], [25]. Up to now, thin-film LiNbO 3 devices have been demonstrated from a few MHz [26] to 60 GHz [27].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Acoustic Loss in Thin-Film Lithium Niobate: An Experimental Study

J. Microelectromech. Syst.

Gong

2021

This work reports an experimental study of acoustic loss in thin-film lithium niobate (LiNbO 3 ) using acoustic delay lines (ADLs). Unlike prior resonator-based quality factor ( Q) studies, this approach directly extracts the damping in thinfilm LiNbO 3, avoiding the influence of other intricate loss mechanisms, e.g., anchor loss and electrode-induced loss. Acoustic attenuation of fundamental symmetric (S0) and shear horizontal (SH0) waves are studied in suspended LiNbO 3 thin films of different thicknesses. The attenuation is significantly higher in thinner LiNbO 3 films, suggesting the LiNbO 3 crystal degradation during the microfabrication as the primary loss origin. Nevertheless, the extracted equivalent Q in thin-film LiNbO 3 is still higher than reported values, suggesting that anchor design and electrode quality remain the bottlenecks for higher Q. The proposed loss extraction framework is readily extendable to other acoustic thin-film structures.