scholarly journals A Study on the Effects of Bottom Electrode Designs on Aluminum Nitride Contour-Mode Resonators

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 758
Author(s):  
Soon In Jung ◽  
Chaehyun Ryu ◽  
Gianluca Piazza ◽  
Hoe Joon Kim
Keyword(s):  
Aluminum Nitride ◽  
Electromechanical Coupling ◽  
Bottom Electrode ◽  
Coverage Rate ◽  
Resonant Frequencies ◽  
Sensing Applications ◽  
Electrode Coverage ◽  
Coverage Rates ◽  
Contour Mode ◽  
The Impact

This study presents the effects of bottom electrode designs on the operation of laterally vibrating aluminum nitride (AlN) contour-mode resonators (CMRs). A total of 160 CMRs were analyzed with varying bottom electrode areas at two resonant frequencies (f0) of about 230 MHz and 1.1 GHz. Specifically, we analyzed the impact of bottom electrode coverage rates on the resonator quality factor (Q) and electromechanical coupling (k2), which are important parameters for Radio Frequency (RF) and sensing applications. From our experiments, Q exhibited different trends to electrode coverage rates depending on the device resonant frequencies, while k2 increased with the coverage rate regardless of f0. Along with experimental measurements, our finite element analysis (FEA) revealed that the bottom electrode coverage rate determines the active (or vibrating) region of the resonator and, thus, directly impacts Q. Additionally, to alleviate thermoelastic damping (TED) and focus on mechanical damping effects, we analyzed the device performance at 10 K. Our findings indicated that a careful design of bottom electrodes could further improve both Q and k2 of AlN CMRs, which ultimately determines the power budget and noise level of the resonator in integrated oscillators and sensor systems.

scholarly journals Temperature Characteristics of a Contour Mode MEMS AlN Piezoelectric Ring Resonator on SOI Substrate

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 143
Author(s):  
Sitao Fei ◽  
Hao Ren
Keyword(s):  
Quality Factor ◽  
Bottom Electrode ◽  
Temperature Stability ◽  
Cryogenic Cooling ◽  
Silicon On Insulator ◽  
Temperature Hysteresis ◽  
Sensing Applications ◽  
Doped Silicon ◽  
Heavily Doped ◽  
Contour Mode

As a result of their IC compatibility, high acoustic velocity, and high thermal conductivity, aluminum nitride (AlN) resonators have been studied extensively over the past two decades, and widely implemented for radio frequency (RF) and sensing applications. However, the temperature coefficient of frequency (TCF) of AlN is −25 ppm/°C, which is high and limits its RF and sensing application. In contrast, the TCF of heavily doped silicon is significantly lower than the TCF of AlN. As a result, this study uses an AlN contour mode ring type resonator with heavily doped silicon as its bottom electrode in order to reduce the TCF of an AlN resonator. A simple microfabrication process based on Silicon-on-Insulator (SOI) is presented. A thickness ratio of 20:1 was chosen for the silicon bottom electrode to the AlN layer in order to make the TCF of the resonator mainly dependent upon heavily doped silicon. A cryogenic cooling test down to 77 K and heating test up to 400 K showed that the resonant frequency of the AlN resonator changed linearly with temperature change; the TCF was shown to be −9.1 ppm/°C. The temperature hysteresis characteristic of the resonator was also measured, and the AlN resonator showed excellent temperature stability. The quality factor versus temperature characteristic was also studied between 77 K and 400 K. It was found that lower temperature resulted in a higher quality factor, and the quality factor increased by 56.43%, from 1291.4 at 300 K to 2020.2 at 77 K.

Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality

2020 ◽  
Vol 90 (3) ◽  
pp. 30502
Author(s):  
Alessandro Fantoni ◽  
João Costa ◽  
Paulo Lourenço ◽  
Manuela Vieira
Keyword(s):  
Amorphous Silicon ◽  
High Throughput Screening ◽  
Simulation Analysis ◽  
Low Cost ◽  
Deposition Process ◽  
Large Area ◽  
Sidewall Roughness ◽  
Sensing Applications ◽  
Fabrication Defects ◽  
The Impact

Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

scholarly journals Racial Differences in Incident Genitourinary Cancer Cases Captured in the National Cancer Database

Medicina ◽  
2021 ◽  
Vol 57 (7) ◽  
pp. 671
Author(s):  
Dylan T. Wolff ◽  
Thomas F. Monaghan ◽  
Danielle J. Gordon ◽  
Kyle P. Michelson ◽  
Tashzna Jones ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
United States ◽  
Bladder Cancer ◽  
Kidney Cancer ◽  
The United States ◽  
Coverage Rate ◽  
National Cancer Database ◽  
Genitourinary Cancer ◽  
Coverage Rates ◽  
Capture Rates

Background and Objectives: The National Cancer Database (NCDB) captures nearly 70% of all new cancer diagnoses in the United States, but there exists significant variation in this capture rate based on primary tumor location and other patient demographic factors. Prostate cancer has the lowest coverage rate of all major cancers, and other genitourinary malignancies likewise fall below the average NCDB case coverage rate. We aimed to explore NCDB coverage rates for patients with genitourinary cancers as a function of race. Materials and Methods: We compared the incidence of cancer cases in the NCDB with contemporary United States Cancer Statistics data. Results: Across all malignancies, American Indian/Alaskan Natives subjects demonstrated the lowest capture rates, and Asian/Pacific Islander subjects exhibited the second-lowest capture rates. Between White and Black subjects, capture rates were significantly higher for White subjects overall and for prostate cancer and kidney cancer in White males, but significantly higher for bladder cancer in Black versus White females. No significant differences were observed in coverage rates for kidney cancer in females, bladder cancer in males, penile cancer, or testicular cancer in White versus Black patients. Conclusions: Differential access to Commission on Cancer-accredited treatment facilities for racial minorities with genitourinary cancer constitutes a unique avenue for health equity research.

Application of Aluminum Nitride Thin Film for Micromachined Ultrasonic Transducers

2005 ◽  
Vol 892 ◽  
Author(s):  
Qianghua Wang ◽  
Jianzeng Xu ◽  
Changhe Huang ◽  
Gregory W Auner
Keyword(s):  
Thin Films ◽  
Aluminum Nitride ◽  
Ultrasonic Transducers ◽  
X Ray Diffraction ◽  
Effective Coupling ◽  
Resonant Frequencies ◽  
X Ray ◽  
Coupling Factors ◽  
Sandwiched Structure

AbstractThis paper reports the fabrication and characterization of micromachined ultrasonic transducers (MUT) based on piezoelectric aluminum nitride (AlN) thin films. The MUT device is composed of an Al/AlN/Al sandwiched structure overlaid on top of a silicon (Si) diaphragm. X-ray diffraction (XRD) scan shows that highly c-axis oriented AlN (002) thin films have been grown on Al/Si(100) substrates. Electrical impedance of the MUT devices is analyzed as a function of frequency. The fundamental resonant frequencies of the devices are found in the range of 65-70 kHz, which are in approximation to the theoretical calculation. The effective coupling factors of the devices are also derived as 0.18.

Fabrication Methods for Improved Electromechanical Behavior in Piezoelectric Membranes

2005 ◽  
Vol 872 ◽  
Author(s):  
M.C. Robinson ◽  
P.D. Hayenga ◽  
J.H. Cho ◽  
C.D. Richards ◽  
R.F. Richards ◽  
...  
Keyword(s):  
Residual Stress ◽  
Electromechanical Coupling ◽  
Silicon Oxide ◽  
Piezoelectric Materials ◽  
Electrical Energy ◽  
Fabrication Technique ◽  
Simply Supported ◽  
Electromechanical Behavior ◽  
Pzt Films ◽  
Electrode Coverage

AbstractPiezoelectric materials convert mechanical to electrical energy under stretching and bending conditions. Optimizing the coupling conversion is imperative to the electromechanical behavior of a micromachined membrane's performance. This paper discusses analytical calculations that were devised to determine the microscale structure that minimizes residual stress and outlines the implementation of fabrication technique variations including three different electrode configurations, trenching around the membrane, and reducing the total composite residual stress of the support structure using compressive silicon oxide. Lead zirconacte titanate (PZT) films between 1 and 3 μm thick with a ratio of Zr to Ti of 40:60 were deposited onto 3 mm square silicon membranes. The total tensile stress in the composite structure reaches 100 MPa during standard fabrication processing. Utilizing analytical calculations, a structure was determined that lowered the residual stress of the composite to 11 MPa and increased the electromechanical coupling 35 times. Changing the geometry of the electrode coverage decreased the residual stress of the composite by 40%. Trenching around the membrane provided a membrane with boundary conditions that approached simply supported and decreased the composite residual stress by another 16%. A comparison of the electromechanical behavior for these structures will be discussed, showing a route towards increasing electromechanical coupling in PZT MEMS.

scholarly journals Nonlinear Optical Pigments. Two-Photon Absorption in Crosslinked Conjugated Polymers and Prospects for Remote Nonlinear Optical Thermometry

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1670
Author(s):  
Jan K. Zaręba ◽  
Marcin Nyk ◽  
Marek Samoć
Keyword(s):  
Solid State ◽  
Conjugated Polymers ◽  
Nonlinear Optical ◽  
Photon Absorption ◽  
Model Compounds ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Sensing Applications ◽  
Spectrally Resolved ◽  
The Impact

Nonlinear optical (NLO) pigments are compounds insoluble in solvents that exhibit phenomena related to nonlinear optical susceptibilities (χ(n) where n = 2,3,...), e.g., two-photon absorption (2PA) which is related to the imaginary part of χ(3). Determination of spectrally-resolved 2PA properties for NLO pigments of macromolecular nature, such as coordination polymers or crosslinked polymers, has long been a challenging issue due to their particulate form, precluding characterizations with standard techniques such as Z-scan. In this contribution, we investigate thus far unknown spectrally-resolved 2PA properties of a new subclass of NLO pigments—crosslinked conjugated polymers. The studied compounds are built up from electron-donating (triphenylamine) and electron-withdrawing (2,2’-bipyridine) structural fragments joined by vinylene (Pol1) or vinyl(4-ethynylphenyl) (Pol2) aromatic bridges. 2PA properties of these polymers have been characterized in broad spectral range by specially modified two-photon excited fluorescence (TPEF) techniques: solid state TPEF (SSTPEF) and internal standard TPEF (ISTPEF). The impact of self-aggregation of aromatic backbones on the 2PA properties of the polymers has been evaluated through extended comparisons of NLO parameters, i.e., 2PA cross sections (σ2) and molar-mass normalized 2PA merit factors (σ2/M) with those of small-molecular model compounds: Mod1 and Mod2. By doing this, we found that the 2PA response of Pol1 and Pol2 is improved 2–3 times versus respective model compounds in the solid state form. Further comparisons with 2PA results collected for diluted solutions of Mod1 and Mod2 supports the notion that self-aggregated structure contributes to the observed enhancement of 2PA response. On the other hand, it is clear that Pol1 and Pol2 suffer from aggregation-caused quenching phenomenon, well reflected in time-resolved fluorescence properties as well as in relatively low values of quantum yield of fluorescence. Accordingly, despite improved intrinsic 2PA response, the effective intensity of two-photon excited emission for Pol1 and Pol2 is slightly lower relative to Mod1 and Mod2. Finally, we explore temperature-resolved luminescence properties under one- (377 nm), two- (820 nm), and three-photon excitation (1020 nm) conditions of postsynthetically Eu3+-functionalized material, Pol1-Eu, and discuss its suitability for temperature sensing applications.

scholarly journals Relationship between Influenza Vaccination Coverage Rate and COVID-19 Outbreak: An Italian Ecological Study

Vaccines ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 535 ◽  
Author(s):  
Mauro Amato ◽  
José Pablo Werba ◽  
Beatrice Frigerio ◽  
Daniela Coggi ◽  
Daniela Sansaro ◽  
...  
Keyword(s):  
Intensive Care ◽  
Influenza Vaccination ◽  
Intensive Care Units ◽  
Vaccination Coverage ◽  
Ad Hoc ◽  
Coverage Rate ◽  
Italian Population ◽  
Vaccination Coverage Rate ◽  
Multivariable Analyses ◽  
Coverage Rates

Background: The lack of specific vaccines or drugs against coronavirus disease 2019 (COVID-19) warrants studies focusing on alternative clinical approaches to reduce the spread of this pandemic disease. In this study, we investigated whether anti-influenza vaccination plays a role in minimizing the diffusion of COVID-19 in the Italian population aged 65 and over. Methods: Four COVID-19 outcomes were used: severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence, hospitalizations for COVID-19 symptoms, admissions to intensive care units for reasons related to SARS-CoV-2, and deaths attributable to COVID-19. Results: At univariate analyses, the influenza vaccination coverage rates correlated negatively with all COVID-19 outcomes (Beta ranging from −134 to −0.61; all p < 0.01). At multivariable analyses, influenza vaccination coverage rates correlated independently with SARS-CoV-2 seroprevalence (Beta (95% C.I.): −130 (−198, −62); p = 0.001), hospitalizations for COVID-19 symptoms (Beta (95% C.I.): −4.16 (−6.27, −2.05); p = 0.001), admission to intensive care units for reasons related to SARS-CoV-2 (Beta (95% C.I.): −0.58 (−1.05, −0.12); p = 0.017), and number of deaths attributable to COVID-19 (Beta (95% C.I.): −3.29 (−5.66, −0.93); p = 0.010). The R2 observed in the unadjusted analysis increased from 82% to 159% for all the considered outcomes after multivariable analyses. Conclusions: In the Italian population, the coverage rate of the influenza vaccination in people aged 65 and over is associated with a reduced spread and a less severe clinical expression of COVID-19. This finding warrants ad hoc studies to investigate the role of influenza vaccination in preventing the spread of COVID-19.

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