Surface Acoustic Wave Devices Using Lithium Niobate on Silicon Carbide

Abstract

This work demonstrates a group of shear horizontal (SH0) mode resonators and filters using lithium niobate (LiNbO 3) thin films on silicon carbide (SiC). The single-crystalline X-cut LiNbO 3 thin films on 4H-SiC substrates have been prepared by ion-slicing and wafer-bonding processes. The fabricated resonator has demonstrated a large effective electromechanical coupling (k 2) of 26.9% and a high-quality factor (Bode-Q) of 1228, hence resulting in a high figure of merit (FoM = k 2 • Bode-Q) of 330 at 2.28 GHz. Additionally, these fabricated resonators show scalable resonances from 1.61 to 3.05 GHz and impedance ratios between 53.2 and 74.7 dB. Filters based on demonstrated resonators have been demonstrated at 2.16 and 2.29 GHz with sharp roll-off and spurious-free responses over a wide frequency range. The filter with a center frequency of 2.29 GHz shows a 3-dB fractional bandwidth of 9.9%, an insertion loss of 1.38 dB, an out-of-band rejection of 41.6 dB, and a footprint of 0.75 mm 2. Besides, the fabricated filters also show a temperature coefficient of frequency of −48.2 ppm/ • C and power handling of 25 dBm. Although the power handling is limited by arc discharge and migration-induced damage of the interdigital electrodes and some ripples in insertion loss and group delay responses are still present due to the transverse spurious modes, the demonstrations still show that acoustic devices on the LiNbO 3-on-SiC platform have great potential for radio-frequency applications.

Strain Balanced Self‐Supporting Single‐Crystalline LiNbO3 Thin Films for Flexible Electronics

“…[22] In recent years, lithium niobate, an artificial crystal with exceptional electro-optical, pyroelectric, ferroelectric, and piezoelectric properties, has regained widespread attention. A new generation of optical and acoustic devices have been realized on ion sliced single-crystalline LiNbO 3 (LN) thin films on heterogeneous substrates (e.g., LiNbO 3 -on-Si [23] and LiNbO 3on-SiC [24] ), such as the integrated electro-optic modulators, [25][26] acousto-optic modulators, [27][28] pyroelectric detectors, [29] and radio frequency (RF) acoustic wave devices. [30][31][32] As a multifunctional material, LN also has great potential for applications in flexible electronics in theory, such as temperature or stress sensors, [33] Terahertz Spectrometer, [34] and RF communication devices.…”

State of the Art in Crystallization of LiNbO3 and Their Applications

“…Radio-frequency (RF) acoustic devices are an essential part of the front ends for emerging applications in 5G and IoT [47][48][49]. In SAW devices, the acoustic wave was propagated along the surface of a piezoelectric material.…”

“…Periodic metallic bars on a piezoelectric material, called IDT electrodes, were used to excite and receive waves with frequencies of up to several GHz. Thus, the piezoelectric substrate is very important, which need a high electromechanical coupling factor, high quality factor, large acoustic velocity, and low acoustic loss [48]. Among different piezoelectric materials, owing to its electromechanical coupling factor of 5.5%, quality (Q) factor of 10 5 , acoustic velocity of 3400-4000 m/s, high thermal (T c = 1140 • C) and chemical stability, LiNbO 3 has been served as important piezoelectric substrate for SAW devices [50].…”

Measuring bulk and surface acoustic modes in diamond by angle-resolved Brillouin spectroscopy

“…The use of micro-acoustic devices greatly shrunk the size of signal processor in the field of communications. With the rapid development of the mobile communications, more high-frequency and highpower acoustic wave devices will be needed [9] .…”