Bulk Acoustic Resonator Research Articles

High-coherence quantum acoustics with planar superconducting qubits

Quantum acoustics is an emerging platform for hybrid quantum technologies enabling quantum coherent control of mechanical vibrations. High-overtone bulk acoustic resonators (HBARs) represent an attractive mechanical implementation of quantum acoustics due to their potential for exceptionally high mechanical coherence. Here, we demonstrate an implementation of high-coherence HBAR quantum acoustics integrated with a planar superconducting qubit architecture, demonstrating an acoustically induced-transparency regime of high cooperativity and weak coupling, analogous to the electrically induced transparency in atomic physics. Demonstrating high-coherence quantum acoustics with planar superconducting devices enables interesting applications for acoustic resonators in quantum technologies.

A novel high-Q Lamé mode bulk acoustic resonator

This study introduces a novel high-Q Lamé mode MEMS resonator, optimized through support beam structures and etching hole distributions to minimize anchor losses and thermal elastic dissipation (TED). Fabricated using a Silicon-On-Insulator (SOI) process, the resonators achieved Q values of 129,200 and 102,100 in different designs, demonstrating significant improvements in vacuum conditions and highlighting air damping as a key loss mechanism. Nonlinear analysis revealed material nonlinearity dominance. These findings offer valuable guidelines for developing high-end MEMS devices, such as low phase noise oscillators and high-resolution sensors, by showcasing substantial reductions in energy dissipation and enhanced Q factors through structural optimizations.

Ultrasensitive liquid sensor based on an embedded microchannel bulk acoustic wave resonator

The high-frequency and high-quality factor characteristics of bulk acoustic wave (BAW) resonators have significantly advanced their application in sensing technologies. In this work, a fluidic sensor based on a BAW resonator structure is fabricated and investigated. Embedded microchannels are formed beneath the active area of the BAW device without the need for external processes. As liquid flows through the microchannel, pressure is exerted on the upper wall (piezoelectric film) of the microchannel, which causes a shift in the resonant frequency. Using density functional theory, we revealed the intrinsic mechanism by which piezoelectric film deformation influences BAW resonator performance. Theoretically, the upwardly convex piezoelectric film caused by liquid flow can increase the resonant frequency. The experimental results obtained with ethanol solutions of different concentrations reveal that the sensor, which operates at a high resonant frequency of 2.225 GHz, achieves a remarkable sensitivity of 5.1 MHz/% (221 ppm/%), with an ultrahigh linearity of 0.995. This study reveals the intrinsic mechanism of liquid sensing based on BAW resonators, highlights the potential of AlN/Al0.8Sc0.2N composite film BAW resonators in liquid sensing applications and offers insights for future research and development in this field.

Highly Doped Single Crystal Al₁-ₓScₓN Bulk Acoustic Resonators for High-Frequency and Wideband Applications

Highly Doped Single Crystal Al₁-ₓScₓN Bulk Acoustic Resonators for High-Frequency and Wideband Applications

Broadband magnetoelectric antenna driven by multiple high-overtone bulk acoustic wave modes

High-overtone bulk acoustic waves driven magnetoelectric (ME) antennas operate in the acoustic resonant frequency range, exhibiting continuous narrowband electromagnetic radiation. ME antennas based on cooperative excitation of multiple high-overtone bulk acoustic waves are expected to achieve broadband performance and are worthy of in-depth exploration. High-overtone bulk acoustic resonator (HBAR) antennas with polished and rough acoustic reflection interfaces were fabricated and tested to investigate the influence mechanisms of acoustic modes in the HBAR on the radiation bandwidth, as well as the relationship between antenna impedance and radiation response. Far-field radiation characteristics indicate that the antenna with rough acoustic reflection interfaces featuring more high-overtone bulk acoustic wave modes suppress radiation dips of up to 5 dB at anti-resonant frequencies without sacrificing radiation gain. The radiation gain of the antenna was calculated using the gain-comparison method to be −35 dBi, with a −3 dB bandwidth of 120 MHz and a fractional bandwidth of up to 11.4%. Finally, a comparison of the radiation characteristics of the HBAR piezoelectric antenna without the magnetic film demonstrates that the broadband radiation of the HBAR ME antenna originates from dynamic magnetic flux driven by high-overtone bulk acoustic waves.

Coherent Acoustic Control of Defect Orbital States in the Strong-Driving Limit

We use a bulk acoustic wave resonator to demonstrate coherent control of the excited orbital states in a diamond nitrogen-vacancy (NV) center at cryogenic temperature. Coherent quantum control is an essential tool for understanding and mitigating decoherence. Moreover, characterizing and controlling orbital states is a central challenge for quantum networking, where optical coherence is tied to orbital coherence. We study resonant multiphonon orbital Rabi oscillations in both the frequency and time domain, extracting the strength of the orbital-phonon interactions and the coherence of the acoustically driven orbital states. We reach the strong-driving limit, where the physics is dominated by the coupling induced by the acoustic waves. We find agreement between our measurements, quantum master-equation simulations, and a Landau-Zener transition model in the strong-driving limit. Using perturbation theory, we derive an expression for the orbital Rabi frequency versus the acoustic drive strength that is nonperturbative in the drive strength and agrees well with our measurements for all acoustic powers. Motivated by continuous-wave spin-resonance-based decoherence protection schemes, we model the orbital decoherence and find good agreement between our model and our measured few-to-several-nanoseconds orbital decoherence times. We discuss the outlook for orbital decoherence protection. Published by the American Physical Society 2024

High-Q film bulk acoustic resonator with high quality AlN film based on transfer method

Thin film bulk acoustic resonator (FBAR) with high quality factor (Q) is preferred for many communication applications. AlN film deposited in conventional FBAR fabrication process is poor, resulting in unsatisfactory device performance. This study demonstrated the comparison of two Si-substrate FBARs, adopting the same AlN deposition process by physical vapor deposition (PVD) method, however using different device fabrication method. Instead of depositing AlN film on Mo/SiO2/Si substrate in existing fabrication process, we deposited AlN directly on Si substrate by PVD to get better crystal quality piezoelectric layer of the FBAR. The full width at half maximum (FWHM) of rocking curve and surface roughness of AlN directly deposited on Si substrate are 1.4° and 1.96 nm, while those of AlN deposited on Mo/SiO2/Si substrate are 8.5° and 5.54 nm, respectively, indicating AlN deposited directly on Si substrate has a better crystal quality than that on Mo/SiO2/Si substrate. The dielectric loss of FBAR using AlN developed on Si substrate decreases from 0.4 Ω to 0.11 Ω leading to the increase of Q m from 470 to 830. By preserving the high quality AlN deposited on Si substate with film transfer method, the FBAR device enjoys an increasing of Q-values as high as 76%.

Stroboscopic x-ray diffraction microscopy of dynamic strain in diamond thin-film bulk acoustic resonators for quantum control of nitrogen-vacancy centers

Stroboscopic x-ray diffraction microscopy of dynamic strain in diamond thin-film bulk acoustic resonators for quantum control of nitrogen-vacancy centers

Bidirectional microwave-optical transduction based on integration of high-overtone bulk acoustic resonators and photonic circuits

Coherent interconversion between microwave and optical frequencies can serve as both classical and quantum interfaces for computing, communication, and sensing. Here, we present a compact microwave-optical transducer based on monolithic integration of piezoelectric actuators on silicon nitride photonic circuits. Such an actuator couples microwave signals to a high-overtone bulk acoustic resonator defined by the silica cladding of the optical waveguide core, suspended to enhance electromechanical and optomechanical couplings. At room temperature, this triply resonant piezo-optomechanical transducer achieves an off-chip photon number conversion efficiency of 1.6 × 10−5 over a bandwidth of 25 MHz at an input pump power of 21 dBm. The approach is scalable in manufacturing and does not rely on superconducting resonators. As the transduction process is bidirectional, we further demonstrate the synthesis of microwave pulses from a purely optical input. Capable of leveraging multiple acoustic modes for transduction, this platform offers prospects for frequency-multiplexed qubit interconnects and microwave photonics at large.

Effect of phase correction produced by trimming layer on thin-film bulk acoustic resonator

Effect of phase correction produced by trimming layer on thin-film bulk acoustic resonator

Investigation of sorptive interactions between volatile organic compounds and supramolecules at dynamic oscillation using bulk acoustic wave resonator virtual sensor arrays

Supramolecules are considered as promising materials for volatile organic compounds (VOCs) sensing applications. The proper understanding of the sorption process taking place in host-guest interactions is critical in improving the pattern recognition of supramolecules-based sensing arrays. Here, we report a novel approach to investigate the dynamic host-guest recognition process by employing a bulk acoustic wave (BAW) resonator capable of producing multiple oscillation amplitudes and simultaneously recording multiple responses to VOCs. Self-assembled monolayers (SAMs) of β-cyclodextrin (β-CD) were modified on four BAW sensors to demonstrate the gas-surface interactions regarding oscillation amplitude and SAM length. Based on the method, a virtual sensor array (VSA) type electronic nose (e-nose) can be realized by pattern recognition of multiple responses at different oscillation amplitudes of a single sensor. VOCs analysis was realized respectively by using principal component analysis (PCA) for individual VOC identification and linear discriminant analysis (LDA) for VOCs mixtures classification.

Design and development of solidly mounted bulk acoustic wave resonator (SMR)-based ammonia gas sensor

Design and development of solidly mounted bulk acoustic wave resonator (SMR)-based ammonia gas sensor

A scandium doped aluminum nitride thin film bulk acoustic resonator

Currently, we stand at the forefront of revolutionary advancements in communication technology. The escalating demands of advanced communication necessitate enhanced performance from materials and radio frequency devices. This paper aims to enhance film performance by depositing scandium-doped aluminum nitride (ScAlN) directly onto a Si substrate. Additionally, ScAlN was deposited on SiO2/AlN/Mo functional layers for comparison purposes. The ScAlN directly deposited on Si demonstrated superior performance in terms of crystalline quality and surface roughness, with a full width at half maximum of 1.7° and a roughness of 1.76 nm. Furthermore, a film bulk acoustic resonator (FBAR) based on the ScAlN film directly deposited on Si was successfully fabricated through thin-film transfer, with critical processes achieved via bonding and wet-etching of the substrate. The ScAlN in the fabricated resonator exhibited a favorable c-axis preferred orientation. The resulting ScAlN-based FBAR displayed a quality factor of 429. This study lays the groundwork for exciting opportunities in the development of higher-performance piezoelectric materials and devices.

Diamond-based HBAR as a high-pressure sensor

Features of an application of a High-overtone Bulk Acoustic Resonator (HBAR) as a high-pressure sensor have been considered. In this way, the second version of an integrated measurement system combining a Diamond Anvil Cell (DAC) and an HBAR operating in the microwave frequency band from 1.3 to 3.7 GHz was developed. A specific configuration of HBAR based on a piezoelectric layered structure as “Al/ASN/Mo/(100) diamond” was proposed. Two independent methods of pressure control were used to calibrate the embedded HBAR as a pressure sensor: a stress-induced shift of the diamond Raman line and the shift of the R1 luminescence line of Cr3+ in the ruby matrix. A stable correlation between the frequency shifts of the acoustic overtones in the HBAR, the shift of the diamond Raman line and the shift of the R1 line with a change in pressure applied to the W-gasket with embedded ruby particles was established in the range of 0 … 30 GPa. The sensitivity of an investigated sensor to the pressure variation was found to be equal 1ΔPΔff=4.8∙10-4GPa-1. The maximal value of 30 GPa obtained in a given work can be easily increased after a minor reconfiguration of the DAC. Considering the range of 0 − 5 GPa a proposed built-in DAC acoustoelectronic sensor has the better performance and sensitivity compared with known methods of a pressure measurement.

Design of Hybrid Bandpass Filter Chips with High Selectivity and Wideband Using IPD and FBAR Technology

A novel hybrid bandpass filter (BPF) with wideband and high selectivity is proposed in this paper. The hybrid BPF is composed of two film bulk acoustic resonator (FBAR) cells and three lumped component resonators realized by the integrated passive device (IPD) technology. The ABCD matrix to S-parameters matrix method is used to calculate the frequency response of the BPF. Moreover, the expressions of transmission zeros (TZs) have been extracted. In the design process, an iterative design approach is proposed to improve the circuit and layout of the hybrid filter based on the packaged acoustic-electric hybrid simulation effect. Finally, two parts of the filter are packaged based on the flip-chip method, and two prototypes for the BPF are measured. The measured results of two chips with 3 dB fractional bandwidth of 13.7% and 15.8% are designed and fabricated, which verifies the validity of the proposed design principle.

Suppression of spurious modes in lateral-excited bulk acoustic wave resonators using piston mode electrodes

Suppression of spurious modes in lateral-excited bulk acoustic wave resonators using piston mode electrodes

Analysis of lattice deformation originated from residual stress on performance of aluminum nitride-based bulk acoustic wave resonators

With the development of MEMS technology to the nanometer scale, the influence of different process conditions on the performance of nano-devices can be calculated through the microscopic changes of materials. During the manufacturing process, the large residual stress from the film stack significantly influences the performance of devices, thereby reducing the wafer yield. Herein, we apply density functional theory to MEMS processes to reveal the intrinsic mechanism of how residual stress affects the performance of aluminum nitride-based bulk acoustic wave (BAW) resonators on an 8-inch high-resistance silicon wafer. The variation rule of physical properties of piezoelectric material aluminum nitride with different residual stresses is calculated via first-principles calculations. Through theory formula derivation, the piezoelectric-coupling constant (Kt2) of the bulk acoustic wave resonator is positively correlated with tensile residual stress, and the resonant frequency (fp, fs) is negatively correlated with tensile residual stress. The measurement results show that the average shifts of Keff2 is 0.12 % within −137 MPa and 183 Mpa residual stress, which is an excellent match with the theory prediction.

Dynamic imaging of micro-vibrations with an ultra-wide bandwidth and a femtometer noise using switchable pulsed laser interferometry

Imaging the complex dynamics of micro-vibrations plays a fundamental role in the investigation of microelectromechanical systems (MEMS). However, it remains a challenge for achieving both a wide bandwidth and a low noise due to the high photodetector noise and electromagnetic interference at GHz frequencies. Here, we propose a pulsed laser interferometry system with an adaptable switch to image GHz vibrations based on stroboscopic mixing, while measuring lower-frequency vibrations based on the homodyne scheme. The noise power spectral density is shown in both regions from DC to 10 GHz with an average noise down to 30.8 fm/√Hz at GHz frequencies, which holds the highest resolution to the best of our knowledge. Vibrational amplitude and phase mappings of a kHz comb-drive resonator, a GHz piezoelectric transducer, and a GHz film bulk acoustic resonator are presented with animated visualizations and k-space analysis, paving a new paradigm for the first time to image and analyze various MEMS devices of a bandwidth spanning 10 orders of magnitude.

Aluminium Scandium Nitride Thin Film BAW Resonators (FBAR) for 5G Applications

With the growing impact of 5G communication system, Radio-Frequency Micro-Electro-Mechanical-Systems (RF MEMS) technologies are becoming increasingly important in our daily lives. Development of filters in the 5G frequency range is being carried out tremendously. The rapid rise in smartphone usage, heightened data demands, congestion in the frequency spectrum, and advancements in technology have posed numerous challenges for the development of RF filters. The ultimate goal is to simplify the RF Front End Module used in smart phones, thereby achieving better selectivity. In this paper, a high frequency - high Q thin film bulk acoustic wave resonator of piezoelectric material Aluminium scandium nitride (AlScN)based FBAR is designed for 5G Application. Finite element analysis conducted using the COMSOL Multiphysics software assess the characteristics of the constructed FBAR. The outcomes indicate that the device resonates effectively at 5 GHz, exhibiting commendable return loss and a Q-factor of 1490. A high-resonance-frequency FBAR device offers advantages for 5G mobile technology.

Comparison of aluminum nitride thin films prepared by magnetron sputter epitaxy in nitrogen and ammonia atmosphere

Wurtzite-type aluminum nitride (AlN) thin films exhibiting high thermal conductivity, large grain size, and low surface roughness are desired for both bulk acoustic wave and surface acoustic wave resonators. In this work, we use ammonia (NH3) assisted reactive sputter deposition of AlN to significantly improve these properties. The study shows a systematic change in the structural, thermal, and morphological properties of AlN grown in nitrogen (N2) and N2 + NH3 atmosphere. The study demonstrates that NH3 assisted AlN sputtering facilitates 2D growth. In addition, the study presents a growth model relating the 2D growth to improve the mobility of aluminum (Al) and nitrogen (N) ad-atoms in NH3 atmosphere. Consequently, the thermal conductivity and roughness improve by ≈76%, and ≈35%, while the grain size increases by ≈78%.