Study Of Pressure Sensor And Ultraviolet Detector Based On Surface Acoustic Wave

The surface acoustic wave is a kind of wave that propagates on the surface of elastic solid,it was applied in communication,radio and signal processing at first.The surface acoustic wave normally propagates in no deep than one wave length away from the surface of piezoelectric materials.The surface acoustic wave devices are quite sensitive to the turbulence from outside environment.The surface acoustic wave sensors are stable,anti-jamming,with high precision and low cost.The most important thing is that they can work in passive wireless mode make it a broad application prospect.In this thesis,the working principle,device structure and design parameters of single port surface acoustic wave resonator are introduced.The common piezoelectric materials used in surface acoustic wave devices are also introduced.Based on current experimental conditions,the design of single port surface acoustic wave resonator based on Zinc Oxide piezoelectric film and Lithium Niobate piezoelectric crystal material is proposed.With support of simulation data,surface acoustic wave resonator with period of 2.4?m based on Zinc Oxide substrate is fabricated through electron beam lithography,and the center frequency is 1.02 GHz.Surface acoustic wave resonator with period of 8 ?m based on 128°Y-X Lithium Niobate is fabricated through ultraviolet image reversal lithography,and the center frequency is 496 MHz.Some process problems of image reversal lithography based on AZ 5214E photoresist have been discussed and some solutions have been proposed.The standard process and parameters of micron level image reversal lithography is conclused.The surface acoustic wave resonator based on Lithium Niobate is integrated with 3D printed chamber to work as a temperature and pressure sensor.In pressure range from 0 to 500 kPa,the pressure sensor has a frequency shift of 0.14 MHz with good linearity.The high frequency surface acoustic wave resonator based on Zinc Oxide combined with 2-dimentional nanosheet Molybdenum Disulfide work as an ultraviolet detector under 365 nm and 254 nm ultraviolet illumination.Under power density of 1.466 mW/cm2,the detector has a frequency shift of 3.5 MHz with good linearity.This thesis fabricates the surface acoustic wave device with feature size of 600 nm and 2 ?m based on electron beam lithography and ultraviolet lithography,respectively.Combining with nano materials and 3D printed devices,these surface acoustic wave devices can work as ultraviolet detector and pressure sensor.This thesis solves the problems of high resolution image reversal lithography based on AZ 5214E photoresist.This thesis implements the image reversal and metal lift-off process of high resolution transducer arrays,which is helpful for future high resolution image lithography.