Radiofrequency Device Research Articles

A Laterally Excited Bulk Acoustic Wave Resonator Based on LiNbO3 with Arc-Shaped Electrodes

High frequency and large bandwidth are growing trends in communication radio-frequency devices. The LiNbO3 thin film material is expected to become the preferred piezoelectric material for high coupling resonators in the 5G frequency band due to its ultra-high piezoelectric coefficient and low loss characteristics. The main mode of laterally excited bulk acoustic wave resonators (XBAR) have an ultra-high sound velocity, which enables high-frequency applications. However, the interference of spurious modes is one of the main reasons hindering the widespread application of XBAR. In this paper, a Z-cut LiNbO3 thin film-based XBAR with arc-shaped electrodes is presented. We investigate the electric field distribution of the XBAR, while the irregular boundary of the arc-shaped electrodes affects the electric field between the existing interdigital transducers (IDTs). The mode shapes and impedance response of the XBAR with arc-shaped electrodes and the XBARs with traditional IDTs are compared in this work. The fabricated XBAR on a 350 nm Z-cut LiNbO3 thin film with arc-shaped electrodes operating at over 5 GHz achieves a high effective electromechanical coupling coefficient of 29.8% and the spurious modes are well suppressed. This work promotes an XBAR with an optimized electrode design to further achieve the desired performance.

A Computational Study on Effects of PID Temperature Target and RF Frequency for PID-Controlled Nonablative RF Cosmetic Systems.

Commonly adopted in cosmetic dermatology, nonablative radiofrequency (RF) devices convert high-frequency electromagnetic energy into thermal energy to induce a wound-healing response in skin tissue. However, differences in the electrical properties of different skin layers raise questions about the impact of different RF frequencies and target temperatures on treatment effectiveness. This paper presents a finite element analysis (FEA)-based computational study aimed at simulating and optimizing the effects of a proportional integral derivative (PID)-controlled RF cosmetic devices under different combinations of these two parameters during treatment. A 3D physical model for the application of a nonablative RF device was constructed using COMSOL, which included the human tissue and RF electrodes, electromagnetic and thermal boundary conditions, as well as the PID controller. FEA was performed for each of the twelve models with parameter combinations of three RF frequencies (0.1, 0.5, and 1 MHz) and three PID-controlled target temperatures (60°C, 65°C, and 70°C) plus one group without PID control. Treatment effectiveness was quantitatively assessed using the integration of tissue thermal damage fraction, i.e., thermal damage volume. In the earlier stage of heating (0-10 s), higher RF frequency resulted in a larger thermal damage volume. At 10 s, among models with a temperature target of 70°C, there is a 6.04% difference between the thermal damage volume at RF frequencies of 1.0 and 0.1 MHz. In the later stage of heating(11-80 s), the impact of RF frequency decreases. The difference in thermal damage volume caused by higher temperature targets is more significant, at 80 s, among models with an RF frequency of 1.0 MHz, the 70°C model produces 1.15 and 1.36 times more tissue thermal damage than the 65°C and 60°C models. PID controller has ensured treatment safety and uniformity, in exchange for some efficiency. Among 12 parameter combinations, the one with a temperature of 70°C and RF frequency of 1.0 MHz achieved the highest thermal damage volume, which could potentially result in the best esthetic effect. Considering users' different susceptibility to heat, engineers or physicians can select better temperature targets and RF frequencies to bring the desired cosmetic results based on thermal damage volume curves from this study.

Does radiofrequency radiation impact sleep? A double-blind, randomised, placebo-controlled, crossover pilot study

The most common source of Radiofrequency Electromagnetic Field (RF-EMF) exposures during sleep includes digital devices, yet there are no studies investigating the impact of multi-night exposure to electromagnetic fields emitted from a baby monitor on sleep under real-world conditions in healthy adults. Given the rise in the number of people reporting to be sensitive to manmade electromagnetic fields, the ubiquitous use of Wi-Fi enabled digital devices and the lack of real-world data, we investigated the effect of 2.45 GHz radiofrequency exposure during sleep on subjective sleep quality, and objective sleep measures, heart rate variability and actigraphy in healthy adults. This pilot study was a 4-week randomised, double-blind, crossover trial of 12 healthy adults. After a one-week run-in period, participants were randomised to exposure from either an active or inactive (sham) baby monitor for 7 nights and then crossed over to the alternate intervention after a one-week washout period. Subjective and objective assessments of sleep included the Pittsburgh Insomnia Rating Scale (PIRS-20), electroencephalography (EEG), actigraphy and heart rate variability (HRV) derived from electrocardiogram. Sleep quality was reduced significantly (p < 0.05) and clinically meaningful during RF-EMF exposure compared to sham-exposure as indicated by the PIRS-20 scores. Furthermore, at higher frequencies (gamma, beta and theta bands), EEG power density significantly increased during the Non-Rapid Eye Movement sleep (p < 0.05). No statistically significant differences in HRV or actigraphy were detected. Our findings suggest that exposure to a 2.45 GHz radiofrequency device (baby monitor) may impact sleep in some people under real-world conditions however further large-scale real-world investigations with specified dosimetry are required to confirm these findings.

Bipolar Radiofrequency Combined with Non-Crosslinked Hyaluronic Acid Mesotherapy: A Protocol for Skin Enhancement

Changes associated with aging, such as alterations in epidermal hydration, pigmentation, thickness, and cell renewal, impact skin appearance and may result in laxity, dryness, and uneven skin tone. This case series aimed to evaluate the combined effects of bipolar radiofrequency and non-crosslinked hyaluronic acid mesotherapy on skin appearance, with the goal of achieving synergistic benefits. This retrospective data analysis included subjects aged 33-67 years with facial skin dryness and laxity. Subjects received treatment with a bipolar radiofrequency device on the face, followed immediately by mesotherapy with 2.5 ml of non-crosslinked hyaluronic acid. Photographic documentation and skin analysis were conducted before treatment and 30 days post-treatment. Fourteen subjects with a mean age of 45 years (range 33-67) and presenting with dry, lax facial skin were included. All measured indicators showed significant improvement following the combined radiofrequency and mesotherapy protocol. The combined protocol also correlated with greater improvement in both patient and physician satisfaction, observed immediately after the procedure and at 30 days post-procedure. The treatment was well tolerated, and no adverse events were reported. The combination of bipolar radiofrequency and non-crosslinked hyaluronic acid mesotherapy resulted in significant improvements in skin appearance, firmness, tone, and overall subject satisfaction compared to the baseline condition. The treatments were well received, leading to noticeable enhancements in facial aesthetics. No adverse events were reported, confirming the safety of the protocol.

Pulsed Wave Mode of Fractional Radiofrequency Microneedling as a New Advance in the Treatment of Inflammatory Acne Vulgaris

Inflammatory acne vulgaris (IAV) is a common skin condition characterized by the presence of reddish, inflamed, and painful lesions on the skin. IAV can drastically affect individuals, specifically their self-esteem, psychological health, and quality of their life in general. Despite new advances in the field, traditional treatment modalities withstand many challenges. Hence, in the current study, we sought to assess the efficacy and safety of a new pulsed wave mode of the fractional microneedling radiofrequency device in the treatment of IAV. This advanced technique employs insulated microneedles to administer energy to the deep dermis without causing damage to the epidermis. Eighty patients (40 males, 40 females, age 21 ± 3, Fitzpatrick skin type III and IV), with acne severity ranging from moderate to severe, were employed in this trial. They were randomly assigned into two groups, 40 patients each. The treated group (A) underwent four sessions of fractionated microneedle RF, 1.5-month apart, whereas group B was designated as the control group that received placebo treatment. Six months following the last session, the degree of improvement assessed by the quantity of IAV lesions and the overall skin appearance in terms of facial pores, sebum excretion, scar, skin tone, and texture. The RF-treated group showed significant improvement compared to the control group after the follow-up period (p-value = 0.0071). Regarding safety, very mild adverse effects were reported, such as discomfort during the session, pinpoint hemorrhage, and erythema, with no major side effects such as burns, scarring, hyperpigmentation, or hypopigmentation were reported. Thus, our data suggest a potential role of the fractional microneedling radiofrequency device in IAV treatment that is both effective and safe.

Scarless Enhanced Body Contouring.

A helium-based plasma device with minimal invasiveness selectively heats tissues via joule heating, ensuring safe external temperatures and eliminating the need to monitor the epidermal temperature. From December 2022 to January 2024, Forty-six patients without prior bariatric surgery, who had localized lipodystrophy and mild-to-moderate skin laxity in various body areas, were enrolled in this prospective work. Liposuction was paired with a helium-based plasma radiofrequency device used for all patients. Data on demographics and postoperative complications were disclosed. A patient evaluation was conducted objectively and subjectively, using an independent plastic surgeon assessment and a patient satisfaction survey, respectively. Our technique was performed on 40 females (87%) and six males (13%), in various body areas: arm (fourteen cases: 30.4%), neck (ten: 21.7%), thigh (nine: 19.6%), abdomen (seven: 15.2%), back (three: 6.5%), gynecomastia (three: 6.5%), their age ranges from 23 to 57years, and their body mass index (BMI) ranges from 24 to 34.6kg/m2. Patients' satisfaction at 6months after surgery was 82.6% (38) satisfied, 15.2% (7) borderline, and 2.2% (1) unsatisfied. Individual plastic surgeon evaluation was 69.6% (32) excellent, 28.3% (13) good, and 2.1% (1) fair. The overall complications rates were postoperative edema in 22 cases (47.8%), ecchymosis in 11 cases (23.9%), persistent skin laxity in one case (11.1%), mild seroma in three cases (6.5%), pain and tingling in six cases (13%), and mild subcutaneous emphysema in four cases (8.7%). Combined liposuction and helium-based plasma radiofrequency device usage are a safe, efficient, and minimally invasive substitute for excisional procedures in non-bariatric patients with localized lipodystrophy and mild-to-moderate skin laxity. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Radiofrequency Improves Facial Fine Lines by Thermal Effect: Damage or Just Stimulation?

Radiofrequency (RF) has been widely used for rejuvenation treatments, but without knowledge of the effective temperature of the target tissues or guidance on treatment parameters, it often leads to adverse reactions and pain. The aim of this study was to demonstrate that thermal stimulation can produce facial rejuvenation effects and to determine the optimal bipolar RF treatment parameters for treating facial fine lines. A bipolar RF device combined with CORE Technology was used in this study. Exvivo studies were conducted on both miniature swine and human skin, utilizing thermographic thermometry and histological analysis. Invivo swine studies were conducted using histological analysis and electron microscopy. A clinical trial was conducted, and the results were evaluated using the Alexiades Comprehensive Grading Scale (ACGS) and Global Aesthetic Improvement Scale (GAIS) scales. The bipolar RF technology can produce a significant effect by thermally stimulating collagen within just 2 weeks without causing thermal damage. A clinical trial involving 46 patients showed a noticeable rejuvenating effect of the bipolar RF device, especially on fine wrinkles. This study confirmed that thermal stimulation, rather than thermal damage, is sufficient to achieve rejuvenation effects. The study also found a range of bipolar RF treatment parameters that are both safe and effective for facial fine lines.

A Versatile, Machine-Learning-Enhanced RF Spectral Sensor for Developing a Trunk Hydration Monitoring System in Smart Agriculture

This paper comprehensively explores the development of a standalone and compact microwave sensing system tailored for automated radio frequency (RF) scattered parameter acquisitions. Coupled with an emitting RF device (antenna, resonator, open waveguide), the system could be used for non-invasive monitoring of external matter or latent environmental variables. Central to this design is the integration of a NanoVNA and a Raspberry Pi Zero W platform, allowing easy recording of S-parameters (scattering parameters) in the range of the 50 kHz–4.4 GHz frequency band. Noteworthy features include dual recording modes, manual for on-demand acquisitions and automatic for scheduled data collection, powered seamlessly by a single battery source. Thanks to the flexibility of the system’s architecture, which embeds a Linux operating system, we can easily embed machine learning (ML) algorithms and predictive models for information detection. As a case study, the potential application of the integrated sensor system with an RF patch antenna is explored in the context of greenwood hydration detection within the field of smart agriculture. This innovative system enables non-invasive monitoring of wood hydration levels by analyzing scattering parameters (S-parameters). These S-parameters are then processed using ML techniques to automate the monitoring process, enabling real-time and predictive analysis of moisture levels.

Energy-Based Device Management of Nodular Reaction Following Poly-D, L-Lactic Acid Injection for Tear Trough Rejuvenation.

Poly-D,L-lactic acid (PDLLA) is used for tear trough rejuvenation but can cause complications like nodular reactions. This report describes using a radiofrequency device to manage these nodules. A 42-year-old woman developed firm, non-inflammatory nodules 3 weeks after receiving PDLLA (Juvelook) injections in the tear trough area. The nodules were firm and not associated with erythema or tenderness. The monopolar radiofrequency device was used directly on the nodules with 150 shots at an energy level 115 J, 28.75 J/cm². The treatment resulted in complete resolution of the nodules within 24 hours. The radiofrequency treatment effectively resolved the nodular reaction without recurrence, highlighting the device's compatibility with the unique structure of Juvelook's PDLLA. Radiofrequency therapy is effective for managing nodular reactions following PDLLA injections. Further research is needed to optimise protocols and improve the safety of biostimulator treatments in cosmetic procedures.

Control of Additive Manufacturing for Radio Frequency Devices With Spatially Varying Dielectric Properties

Control of Additive Manufacturing for Radio Frequency Devices With Spatially Varying Dielectric Properties

Preliminary Exploration of Low Frequency Low-Pressure Capacitively Coupled Ar-O2 Plasma

Non-thermal plasma as an emergent technology has received considerable attention for its wide range of applications in agriculture, material synthesis, and the biomedical field due to its low cost and portability. It has promising antimicrobial properties, making it a powerful tool for bacterial decontamination. However, traditional techniques for producing non-thermal plasma frequently rely on radiofrequency (RF) devices, despite their effectiveness, are intricate and expensive. This study focuses on generating Ar-O2 capacitively coupled plasma under vacuum conditions, utilizing a low-frequency alternating current (AC) power supply, to evaluate the system’s antimicrobial efficacy. A single Langmuir probe diagnostic was used to assess the key plasma parameters such as electron density (ne), electron temperature (Te), and electron energy distribution function (EEDF). Experimental results showed that ne increases (7 × 1015 m−3 to 1.5 × 1016 m−3) with a rise in pressure and AC power. Similarly, the EEDF modified into a bi-Maxwellian distribution with an increase in AC power, showing a higher population of low-energy electrons at higher power. Finally, the generated plasma was tested for antimicrobial treatment of Xanthomonas campestris pv. Vesicatoria. It is noted that the plasma generated by the AC power supply, at a pressure of 0.5 mbar and power of 400 W for 180 s, has 75% killing efficiency. This promising result highlights the capability of the suggested approach, which may be a budget-friendly and effective technique for eliminating microbes with promising applications in agriculture, biomedicine, and food processing.

Readout circuit for a ZnO bulk-acoustic-wave X-ray dose rate detector

Bulk Acoustic Wave (BAW) resonators based on piezoelectric semiconductors are radio frequency devices that can convert X-ray dose rate into resonant frequency offset, which exhibit strong anti-interference capabilities and low power consumption and are suitable for wireless sensing systems. In this study, we designed a readout circuit for a ZnO BAW X-ray dose rate detector. (0001)-oriented ZnO single crystals were used to fabricate the high-quality BAW X-ray detector. Under dark field and X-ray irradiation conditions, the resonant frequency offset of the detector was recorded via the readout circuit. The readout circuit consists of an oscillator circuit based on a Pierce oscillator circuit structure, a frequency mixing circuit, and an STM32 microcontroller. This design offers higher frequency stability and lower phase noise. In practical applications, it can replace the expensive and bulky vector network analyzer for detecting and storing the resonant frequency of BAW resonators with the advantages of fast readout speed and portability.

The impact of energy-based devices on sebum in acne vulgaris: A systematic review.

Acne vulgaris (AV) is a widespread inflammatory skin condition associated with increased sebum production, abnormal keratinization, bacterial overgrowth, and inflammation. Overactive sebaceous glands (SGs) produce excess sebum, promote Cutibacterium acnes growth, and affect acne development. Energy-based treatments (EBDs), including light therapy, photodynamic therapy (PDT), lasers, and radiofrequency (RF) devices, have emerged as effective treatment options. As the use of EBDs becomes more widespread, it is imperative to understand their effects on skin parameters, such as sebum, in AV. Searches were conducted in Embase, PubMed, Web of Science, and the Cochrane Library. The studies included were randomized and nonrandomized trials on facial AV that used EBDs and featured objective casual sebum level (CSL) measurements via Sebumeter. Data synthesis involved percentage reductions in CSL at follow-ups compared to baseline. Twenty-three studies were analyzed. PDT and RF consistently reduced CSL by 30%-40% and 30%-35%, respectively. Laser therapy showed lesser reductions, whereas light therapy varied significantly and studies had a high risk of bias. All EBD therapies were more effective than no treatment and PDT was superior to light monotherapy. Laser therapy combined with fractional microneedling radiofrequency (FMR) or as a standalone was more effective than laser alone. Noninvasive sebum measurement provides valuable insights into AV treatment efficacy. PDT, lasers, especially the 1450-nm diode laser, and FMR are promising for reducing sebum. Standardization of measurement techniques and further research are vital for enhancing treatment personalization, reducing side effects, and improving AV management.

Magnetization dynamics driven by displacement currents across a magnetic tunnel junction

Understanding the high-frequency transport characteristics of magnetic tunnel junctions (MTJs) is crucial for the development of fast-operating spintronics memories and radio frequency devices. Here, we present the study of a frequency-dependent capacitive current effect in CoFeB/MgO-based MTJs and its influence on magnetization dynamics using a time-resolved magneto-optical Kerr effect technique. In our device, operating at gigahertz frequencies, we find a large displacement current of the order of mA, which does not break the tunnel barrier of the MTJ. Importantly, this current generates an Oersted field and spin-orbit torque, inducing magnetization dynamics. Our discovery holds promise for building robust MTJ devices operating under high current conditions, also highlighting the significance of capacitive impedance in high-frequency magnetotransport techniques. Published by the American Physical Society 2024

Enhanced Radiation Efficiency by Resonant Coupling in a Large Bandwidth Magnetoelectric Antenna

AbstractMagnetoelectric (ME) antennas hold the potential for significantly advancing miniaturization in radio frequency devices due to their compact size. However, critical hurdles still remain in ME antennas including low radiation efficiency and narrow bandwidth, which prevent them from seeing widespread use. Here, by sweeping the magnetic field to reach a resonant coupling, a significant enhancement in radiation efficiency by 70.95 ± 6.4% in a broad bandwidth ME antenna with 80 MHz is achieved as well as the far‐field radiation patterns are changed compared with that via non‐resonant coupling. The enhancement depends on the relative orientation between the magnetization and surface acoustic wave propagation direction which is dominated by the symmetry of the driving field induced by shear strain. A larger enhancement occurs when the magnetic field along hard axis of Ni due to the matching helicity and larger strain compared with easy axis scenario. This work demonstrates an innovative methodology that significantly enhances the radiation and reception efficiency in ME antennas, which may provide ideas for subsequent applications in communication antennas and magnetic sensors.

Efficacy and safety of a novel monopolar radiofrequency device with a continuous water-cooling system in patients with age-related facial volume loss

Background Esthetic radiofrequency (RF) technology has much attracted public attention with the increasing demand for skin rejuvenation. A continuous water cooling-based monopolar RF (MRF) device was designed for the first time to protect the epidermis and maximize clinical outcomes. Objective Assess the efficacy and safety of the proposed MRF device in patients with mild-to-moderate sunken cheeks and jawline laxity. Methods Twenty-one patients underwent a single session of MRF treatment. Quantitative analysis was performed using a 3D imaging technique. Postprocedural clinical improvements were assessed with the Merz Scale. Regarding safety, adverse events (AEs), thermal sensation (TS) and pain intensity were explored. Patient satisfaction was surveyed with the Self-Assessment Questionnaire (SAQ). Results The follow-up investigation demonstrated that facial volume increased across the cheek and jawline, with lifting effects throughout the treatment area. The Merz Scale assessment revealed that sunken cheeks, sagging jawlines and wrinkles were markedly improved. In addition, there were transient AEs, mild TS and moderate pain. In SAQ, 81% patients were satisfied with the procedure. Conclusions This study provided quantitative evidence for postprocedural volumetric increases along with enhanced lifting effects, strongly implying that the proposed MRF device can be an attractive option for improving facial skin volume loss and laxity.

Cost‐Effective Conductive Paste for Radiofrequency Devices Using Carbon‐Based Materials

With the increasing demand for compact, lightweight, cost‐effective, and high‐performance radiofrequency (RF) devices, the development of low‐profile antennas becomes crucial. This article presents a study of a novel carbon–cellulose‐based paste intended for screen printing RF devices. The investigation specifically explores the application of high‐reactivity carbon mixture (HRCM) particles as conductive fillers. The results demonstrate that optimal electrical conductivity values and discrete electromagnetic dipole performances can be achieved at lower concentrations of solid conductive material compared to conventional pastes, for similar applications. This offers benefits in terms of total cost, material consumption, and environmental impact. The paste formulation showcases a complex non‐Newtonian behavior, where yielding flow and thixotropicity are found to be independent and dependent on preshear conditions, respectively. This behavior can be attributed to the network orientation and rearrangement of filler structures within the paste system, which in turn are responsible for filler pattern uniformity and overall printing quality. Compared to traditional conductive materials, HRCM pastes are proven to be a viable alternative for RF devices fabrication, including printed Wi‐Fi antennas.

Clinical outcomes of conjunctivochalasis treatment with a new ophthalmic radiofrequency device

PurposeTo investigate the safety and efficacy of a new micro-controlled radiofrequency device for treatment of conjunctivochalasis (Cch).MethodsData of 127 patients (230 eyes) who underwent ophthalmic radiofrequency treatment for Cch from January 2020 to June 2023 were analyzed retrospectively. Cch coagulation was performed with a radiofrequency electrode tip (OcuRF®, Ilooda, Korea) and a high-frequency radio-wave electric unit (0.6 ~ 0.8 watts, 2 MHz, Acutron™, Ilooda, Korea). Pre- and postoperative Cch grading, slit-lamp photography, tear film break-up time (TBUT), and bulbar conjunctival hyperemia using Keratograph 5 M (Oculus, Wetzlar, Germany) were evaluated. Cch grade 0 or 1 after surgery was regarded as ‘success’. Complications, recurrence, and additional treatment rates were analyzed.ResultsIn 227 (98.7%) eyes, the radiofrequency treatment led to marked improvement of Cch, with 224 (97.4%) eyes achieving grade 0 or 1 at 2 months postoperatively. Eight eyes (3.5%) received additional treatment. TBUT improved from 3.17 ± 0.82 s to 5.28 ± 1.10 s after surgery (P < 0.001). The total bulbar conjunctival hyperemia value showed an improvement from 1.7 ± 0.6 to 1.4 ± 0.6 postoperatively (P < 0.05). No serious complications were observed.ConclusionThe novel ophthalmic radiofrequency device led to a marked improvement of Cch with no serious adverse events during the entire follow-up period. Our results suggest that the radiofrequency device presents a safe and efficacious treatment option for Cch.

Differences in the effectiveness and safety of different renal denervation devices.

Renal denervation (RDN) is a minimally invasive, endovascular catheter-based procedure using radiofrequency, ultrasound, or alcohol-mediated ablation to treat resistant hypertension. RDN gained popularity in 2009 when it was shown to have an antihypertensive effect. However, concerns about the efficacy of RDN were raised in the HTN-3 trial published in 2014, and the development of several RDN devices was then discontinued. In the process, new randomized controlled trials were conducted after the development of some of the RDN devices, the quality assurance of the procedure, changes in ablation points, and improvements in study design. In November 2023, the U.S. Food and Drug Administration approved a radiofrequency RDN device and an ultrasound RDN device. The results of a randomized controlled trial of an alcohol-mediated RDN device have been published, and future trends are being watched closely. In this mini-review, we summarize the differences in the antihypertensive effect and safety of the different RDN devices and the endpoints of the procedure in order to contribute to the further development of RDN devices Currently available renal denervation device. A multielectrode radiofrequency ablation (Spyral), (B) ultrasound denervation (Paraise), and (C) alcohol-mediated perivascular denervation (Peregrine). ASBP ambulatory systolic blood pressure, ADBP ambulatory diastolic blood pressure, OSBP office systolic blood pressure, ODBP office diastolic blood pressure. Analysis according to types of renal denervation device (radiofrequency, ultrasound, or alcohol-mediated device). P values for interaction were 0.578 (ambulatory SBP), 0.499 (ambulatory diastolic BP), 0.853 (office SBP), and 0.870 (office diastolic BP).

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.