scholarly journals Love Wave Ultraviolet Photodetector Fabricated on a TiO2/ST-Cut Quartz Structure

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Walter Water ◽  
Yi-Shun Lin ◽  
Chi-Wei Wen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Temperature Coefficient ◽  
Coupling Coefficient ◽  
Love Wave ◽  
Electromechanical Coupling ◽  
Quartz Substrate ◽  
Electromechanical Coupling Coefficient ◽  
Ultraviolet Photodetector ◽  
Temperature Coefficient Of Frequency

A TiO2thin film deposited on a 90° rotated 42°45′ ST-cut quartz substrate was applied to fabricate a Love wave ultraviolet photodetector. TiO2thin films were grown by radio frequency magnetron sputtering. The crystalline structure and surface morphology of TiO2thin films were examined using X-ray diffraction, scanning electron microscope, and atomic force microscope. The effect of TiO2thin film thickness on the phase velocity, electromechanical coupling coefficient, temperature coefficient of frequency, and sensitivity of ultraviolet of devices was investigated. TiO2thin film increases the electromechanical coupling coefficient but decreases the temperature coefficient of frequency for Love wave propagation on the 90° rotated 42°45′ ST-cut quartz. For Love wave ultraviolet photodetector application, the maximum insertion loss shift and phase shift are 2.81 dB and 3.55 degree at the 1.35-μm-thick TiO2film.

Characteristics Analysis of Saw Filter Using Al0.36Ga0.64N Thin Film

2002 ◽  
Vol 720 ◽  
Author(s):  
Sun-Ki Kim ◽  
Min-Jung Park ◽  
Cheol-Yeong Jang ◽  
Hyun-Chul Choi ◽  
Jung-Hee Lee ◽  
...  
Keyword(s):  
Thin Film ◽  
Insertion Loss ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Side Lobe ◽  
Electromechanical Coupling Coefficient ◽  
Device Performance ◽  
Saw Devices ◽  
Characteristics Analysis ◽  
Temperature Coefficient Of Frequency

AbstractAlxGa1-xN sample with x=0.36 was epitaxially grown on sapphire by MOCVD. SAW velocity of 5420 m/s and TCF (temperature coefficient of frequency) of -51.20 ppm/°C were measured from the SAW devices fabricated on the AlxGa1-xN sample, when kh value was 0.078, at temperatures between –30 °C and 60 °C Electromechanical coupling coefficient was ranged from 1.26 % to 2.22 %. The fabricated SAW filter have shown a good device performance with insertion loss of -33.853 dB and side lobe attenuation of 20 dB.

scholarly journals Effects of Thermal Annealing on the Characteristics of High Frequency FBAR Devices

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 397
Author(s):  
Yu-Chen Chang ◽  
Ying-Chung Chen ◽  
Bing-Rui Li ◽  
Wei-Che Shih ◽  
Jyun-Min Lin ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Annealing ◽  
Electromechanical Coupling ◽  
Zno Thin Films ◽  
Electromechanical Coupling Coefficient ◽  
Back Side ◽  
Zno Thin Film ◽  
Frequency Responses ◽  
Sputtering System

In this study, piezoelectric zinc oxide (ZnO) thin film was deposited on the Pt/Ti/SiNx/Si substrate to construct the FBAR device. The Pt/Ti multilayers were deposited on SiNx/Si as the bottom electrode and the Al thin film was deposited on the ZnO piezoelectric layer as the top electrode by a DC sputtering system. The ZnO thin film was deposited onto the Pt thin film by a radio frequency (RF) magnetron sputtering system. The cavity on back side for acoustic reflection of the FBAR device was achieved by KOH solution and reactive ion etching (RIE) processes. The crystalline structures and surface morphologies of the films were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The optimized as-deposited ZnO thin films with preferred (002)-orientation were obtained under the sputtering power of 80 W and sputtering pressure of 20 mTorr. The crystalline characteristics of ZnO thin films and the frequency responses of the FBAR devices can be improved by using the rapid thermal annealing (RTA) process. The optimized annealing temperature and annealing time are 400 °C and 10 min, respectively. Finally, the FBAR devices with structure of Al/ZnO/Pt/Ti/SiNx/Si were fabricated. The frequency responses showed that the return loss of the FBAR device with RTA annealing was improved from −24.07 to −34.66 dB, and the electromechanical coupling coefficient (kt2) was improved from 1.73% to 3.02% with the resonance frequency of around 3.4 GHz.

scholarly journals Surface acoustic wave temperature properties in alpha-GeO2 crystal

2021 ◽  
Vol 2131 (5) ◽  
pp. 052098
Author(s):  
R M Taziev
Keyword(s):  
Wave Propagation ◽  
Surface Wave ◽  
Acoustic Wave ◽  
Temperature Coefficient ◽  
Surface Acoustic Wave ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Propagation Direction ◽  
Electromechanical Coupling Coefficient ◽  
Wave Propagation Direction

Abstract In this study, the surface acoustic wave (SAW) temperature properties in flux-grown α-GeO2 crystal are numerically investigated. It is shown that the SAW velocity temperature change substantially depends only on the temperature coefficient of three elastic constants: C66, C44 and C14 for crystal cuts and wave propagation directions, where SAW has high electromechanical coupling coefficient. The SAW temperature coefficient of delay (TCD) for these crystal cuts are in the range from -40 ppm /°C to -70 ppm /°C. In contrast to alpha-quartz, the surface wave TCD values are not equal to zero in Z-, Y- , and Z- rotated cuts of α-GeO2 single crystal. Its values are comparable in the magnitude with the surface wave TCD values in lithium tantalate. In the crystal grown from the melt, the interdigital transducer (IDT) conductance has two times larger amplitude than that in hydrothermally grown a-GeO2. The leaky acoustic wave excited by IDT on Z+120°-cut and wave propagation direction along the X-axis, has an electromechanical coupling coefficient 5 times less than that for surface wave.

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