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Author(s):  
Takumi Tominaga ◽  
Shinji Takayanagi ◽  
Takahiko Yanagitani

Abstract ScAlN films are currently being investigated for their potential use in surface acoustic wave (SAW) devices for next-generation mobile networks because of their high piezoelectricity. This paper describes the numerical simulation of SAW propagation in c-axis-tilted ScAlN films on silicon substrates and a fabrication technique for preparing c-axis-tilted ScAlN films on silicon substrates. The electromechanical coupling coefficient K 2 of SAW propagating in the ScAlN film/silicon substrate increased due to the c-axis tilt angle. The maximum K 2 value is approximately 3.90%. This value is 2.6 times the maximum K 2 value of the c-axis-oriented ScAlN film/silicon substrate structure. The c-axis-tilted ScAlN films with an Sc concentration of 40% were prepared on a silicon substrate via RF magnetron sputtering based on the self-shadowing effect, and the maximum c-axis tilt angle was 57.4°. These results indicate that this device structure has potential for SAW device applications with well-established micromachining technology derived from silicon substrates.


Author(s):  
Dhruvajyoti Barah ◽  
Subhamoy Sahoo ◽  
Naga Sai Manoj Inaganti ◽  
Haripriya Kesavan ◽  
Jayeeta Bhattacharyya ◽  
...  

Abstract 4,4′-bis[(N-carbazole) styryl] biphenyl (BSB4 or BSBCz) is one of the widely studied organic fluorescent materials for blue organic electroluminescent devices in the recent times. In this work, BSB4 is used as a guest material to construct the host-guest matrix for the emissive layer (EML) of a pure blue fluorescent organic light-emitting diode (OLED). A pure blue emission suitable for display application with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.147, 0.070) is achieved by the blue-shift of the emission spectrum of the host-guest matrix from that of the pristine guest (BSB4) molecules. The optimization of OLED structures is carried out by considering (i) charge balance in the emissive layer for high exciton density, and (ii) optical interference of generated light in the organic layers for increased light outcoupling. A thorough comparative study on the use of different combinations of widely used hole and electron transport layers to obtain charge balance in the EML of the OLED, thereby enhancing the external quantum efficiency (EQE) is shown. Optical interference effects in the fabricated OLEDs are analyzed by optical simulation of each device structure by transfer matrix method (TMM). With the optimized device structures, we are able to overcome the 2% EQE limit that has been reported so far for blue fluorescent OLEDs with BSB4 as light emitting material and achieve a maximum EQE of 4.08%, which is near to the theoretical limit of EQE for fluorescent OLEDs.


Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 390
Author(s):  
Pragya Singh ◽  
Firman Mangasa Simanjuntak ◽  
Li-Lun Hu ◽  
Tseung-Yuen Tseng ◽  
Hsiao-Wen Zan ◽  
...  

Nitric oxide (NO) is a toxic gas, which is dangerous for human health and causes many respiratory infections, poisoning, and lung damage. In this work, we have successfully grown ZnO nanorod film on annealed ZnO seed layer in different ambient temperatures, and the morphology of the nanorods sensing layer that affects the gas sensing response to nitric oxide (NO) gas were investigated. To acknowledge the effect of annealing treatment, the devices were fabricated with annealed seed layers in air and argon ambient at 300 °C and 500 °C for 1 h. To simulate a vertical device structure, a silver nanowire electrode covered in ZnO nanorod film was placed onto the hydrothermal grown ZnO nanorod film. We found that annealing treatment changes the seed layer’s grain size and defect concentration and is responsible for this phenomenon. The I–V and gas sensing characteristics were dependent on the oxygen defects concentration and porosity of nanorods to react with the target gas. The resulting as-deposited ZnO seed layer shows better sensing response than that annealed in an air and argon environment due to the nanorod morphology and variation in oxygen defect concentration. At room temperature, the devices show good sensing response to NO concentration of 10 ppb and up to 100 ppb. Shortly, these results can be beneficial in the NO breath detection for patients with chronic inflammatory airway disease, such as asthma.


2022 ◽  
Author(s):  
Rashi Chandel ◽  
deepak Punetha ◽  
Divya Dhawan ◽  
Neena Gupta

Abstract The perovskite absorber layer are considered highly efficient solar cell for low-cost electricity production. In this research work, an EA-substituted tin based perovskite solar cell with different hole transport material (PEDOT: PSS, Cu2O, CuI, CZTSe) have been investigated using device simulation software. The effects of absorber thickness, defect density, operating temperature, J-V characteristics, and Quantum efficiency have been considered to enhance the performance of solar cell. To confirm the feasibility and validate the study, all the simulation results were compared with reported experiment data. According to the experimental work based on (FA0.9EA0.1)0.98EDA0.01SnI3 absorber layer, maximum of 13% efficiency is achieved with PEDOT: PSS as the HTM. Whereas we have further optimized performance parameters and found the superior response (Voc=0.8851 V, Jsc=27.24 mA/cm2, FF=77.91%, and PCE=18.78%) while opted Cu2O as the hole transport material. This device structure FTO/Cu2O/(FA0.9EA0.1)0.98EDA0.01SnI3/IDL/PCBM/C60/Au provides the more efficient, reliable solution for replacing the lead-based perovskite solar cell. This study will aid researcher in a reasonable choice of materials and to predict the behavior of high performance solar cell before undergoing the fabrication process.


Doklady BGUIR ◽  
2022 ◽  
Vol 19 (8) ◽  
pp. 81-86
Author(s):  
I. Yu. Lovshenko ◽  
A. Yu. Voronov ◽  
P. S. Roshchenko ◽  
R. E. Ternov ◽  
Ya. D. Galkin ◽  
...  

The results of the simulation the influence of the proton flux on the electrical characteristics of the device structure of dual-channel high electron mobility field effect transistor based on GaAs are presented. The dependences of the drain current ID and cut-off voltage on the fluence value and proton energy, as well as on the ambient temperature are shown.


2022 ◽  
Author(s):  
Shayan Mookherjee

This NSF-funded project [0642603] is a five-year (60 months) CAREER (Faculty Early Career Development Program) unified research and education development program, with a focus on the physics and applications of optical waveguiding in the CROW (Coupled Resonator Optical Waveguide) device structure. The CROW structure is suitable as the foundation of this project because it offers a very high four-wave mixing nonlinearity based on the slow-light effects on each of the pump, signal and idler modes. Since the output depends quadratically on the propagation length (in the low power regime), it is important to realize long CROWs.


2021 ◽  
Author(s):  
SNEHAMOYEE HAZRA ◽  
Subhamita Sengupta ◽  
Soumyaranjan Ratha ◽  
Ankita Ghatak ◽  
Arup Kumar Raychaudhuri ◽  
...  

Abstract The high internal resistance of the perovskite materials used in Nanogenerators (NGs) lowers the power generation. It severely restricts their application for mechanical energy harvesting from the ambient source. In this work, we demonstrate a flexible Piezoelectric NG (PENG) with an improved device structure. Hydrothermally grown one-dimensional Lead Zirconate Titanate (Pb(ZrTi)O3) of different morphologies are used as the generating material. The morphology of the PZT nanostructures, engineered from nanoparticles to needle-shaped nanowires to increase the surface to volume ratio, provides effective mechanical contact with the electrode. The reduction of the internal resistance of the PENG has been achieved by two ways: i) fabrication of interdigitated electrodes (IDE) to increase the interfacial polarization and ii) lowering of Schottky barrier height (SBH) at the junction of the PZT nanostructure and the metal electrode by varying the electrode materials of different work functions. We find that lowering of the SBH at the interface contributes to an increased piezo voltage generation. The flexible nano needles-based PENG can deliver output voltage 9.5 V and power density 615 μW/cm2 on application low mechanical pressure (~1 kPa) by tapping motion. The internal resistance of the device is ~0.65 MΩ. It can charge a 35 μF super-capacitor up to 5 V within 20 s. This study provides a systematic pathway to solve the bottlenecks in the piezoelectric nanogenerators due to the high internal resistance.


2021 ◽  
Author(s):  
Lixain Tian ◽  
Aiqing Fan ◽  
Xi Yu ◽  
Wenping Hu

Achieving high rectifying performance of molecular scale diode devices through synthetic chemistry and device construction remain a formidable challenge due to the complexity of the charge transport process and the device structure. We demonstrated here high-performance molecular rectification realized in self-assembled monolayer (SAM) based device by low-cost and fast screening the electroactive units. SAMs of commercial available carboxylate terminated alkane thiols on gold substrate, coordinated with a variety of metal ions, structures denoting as Au-S-(CH2)n-1COO-Mm+ (Cn+Mm+), where n=11, 12, 13, 14, 16, 18 and Mm+=Ca2+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, were prepared and junctions were measured using a eutectic indiumgallium alloy top contact (EGaIn). The C18+Ca2+ and C18+Zn2+ junctions were found to afford a record high rectification ratio (RR) of 756 at ±1.5 V. Theoretical analysis based on single level tunneling model shows that optimized combination of the asymmetry voltage division, energy barrier and the coupling of carboxylate-metal complex with electrode. Our method described here represent a general strategy for fast, cheap and effective exploration of the metal complex chemical space for high-performance molecular diodes devices.


Author(s):  
Junichi SHIOGAI ◽  
Zhenhu Jin ◽  
Yosuke Satake ◽  
Kohei Fujiwara ◽  
Atsushi TSUKAZAKI

Abstract A ferromagnetic nanocrystalline Fe-Sn is an excellent platform for magnetic-field sensor based on anomalous Hall effect (AHE) owing to simple fabrication and superior thermal stability. For improvement of the magnetic-field sensitivity, doping impurity and increasing injection current are effective approaches. However, in the light of magnetic-field detectivity, the large current may increase the voltage noise. In this study, a maximum allowable current of was improved by employing the overlayer electrode configuration on a Ta-doped Fe-Sn AHE sensor. In noise measurements, the 1/f noise becomes significant with increasing the current at low frequency, resulting in saturation of the detectivity to 240 nTHz-1/2 at 120 Hz. At high frequency, the detectivity reaches 48 nTHz-1/2 at 3.1 mA showing ten times improvement of the detectivity compared with the non-doped Fe-Sn AHE sensor. Material design and device structure optimization will accelerate further improvement of the sensing properties of the Fe-Sn-based AHE sensor.


Aerospace ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 401
Author(s):  
Maxime Royon ◽  
Thomas Blanchet ◽  
Muhammad Adnan ◽  
Damien Jamon ◽  
François Royer ◽  
...  

The optimization of a 2D optical sensor based on TiO2–SiO2 sol-gel waveguides for damage detection in the aerospace domain was performed in the framework of the ADD-ON European project. The sensor is based on the transportation of visible light along numerous waveguides, and damage is detected and localized through the monitoring of the output light from the waveguide grid. In this work, we have developed an architecture, inspired by a multi-mode interferometer (MMI), allowing us to efficiently multiply the number of waveguides that can be probed by a single optical source. For this, the beam propagation method (BPM) was used to model a rectangular MMI coupler (40 × 5624 µm2) operating in the visible region (600 nm), ensuring the propagation of light into three waveguides. The conceived device was then manufactured by UV photolithography (direct laser writing technique). The simulations and experimental results show that light transport into this architecture allows for the successful simultaneous probing of three waveguides. By complexifying the device structure, successful MMI couplers were easily manufactured, allowing us to probe 9, 15, or 45 TiO2–SiO2 waveguides with a unique light source. Finally, a further investigation regarding 24 consecutive thermal cycles from −40 °C to 60 °C, representative of the temperature changes during aircraft cruising, was performed. This study reveals that TiO2–SiO2 sol-gel waveguides are not mechanically damaged by temperature changes, while the light guidance remains unaffected, confirming that this sensor is very promising for aerospace applications. Since a single source can monitor several guides, the production of more compact, low-cost, and less intrusive sensors can be achieved by fulfilling structural health monitoring requirements.


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