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Research On 3D Graphene FET Sensor

Posted on:2021-05-17Degree:MasterType:Thesis
Country:ChinaCandidate:S S LiFull Text:PDF
GTID:2381330614972495Subject:Electronic Science and Technology
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As a kind of detecting device,sensors can sense signals and then convert them into measurable outputs.Hence they are considered as the electric sensing organs of human beings,which is the foundation for the interconnected and intelligent world.The currently reported sensors based on graphene materials are mostly designed in two-dimensional?2D?planes,which may exhibit many limitations in applications.For example,the planar2D structures occupy a relative large chip area and limit their performance as sensors.In order to solve these problems,a three-dimensional graphene field-effect transistor?3D GFET?sensor based on silicon nitride?SiNx?membranes,applying self-rolled-up technology has been proposed,whose preparation process,performance and applications are highlighted as following:1.The 3D GFET was designed and fabricated.By using the traditional micro-nano process,the 2D buried-gate GFET with strained silicon nitride?SiNx?nanomembranes was firstly fabricated.The 3D GFET was achieved from the rolling up process of the 2D GFET structure,caused by the strained SiNx membranes.Meanwhile,the controllable fabrication of 3D GFET array with different feature sizes is realized.Various characterization techniques such as scanning electron microscopy and Raman spectroscopy are used to characterize and analyze the structure,materials,and electrical properties of the 3D GFETs.2.The performance of 3D GFET as an ultra-broadband photosensor has been studied,where the photoresponses of the 3D GFET were investigated in ultraviolet,visible,infrared,and terahertz regions.The tubular 3D GFET provides a natural optical resonate microcavity,which not only enhances the optical field inside it,but also increases the graphene-light interaction area.The experimental results demonstrate that our 3D GFET exhibits significant responses to these wavelengths of light.Compared with 2D GFET,the responsivities of 3D GFET are improved by 2-3 orders of magnitude.Meanwhile,it shows an ultra-fast response speed?265 ns?.More surprisingly,the 3D GFET is also sensitive to polarized light.3.The ultraviolet photosensors with ultra-high responsivity have been demonstrated by decorating the surface of both 2D GFET and 3D GFET with titanium dioxide nanoparticles?TiO2 NPs?.For the former,the responsivity of the TiO2 NPs decorated 2D GFET was demonstrated up to 118.3 A W-1,which is attributed to the strong ultraviolet absorption by TiO2 NPs and the superior electrical properties of graphene.For the latter,by combining TiO2 NPs with 3D GFET,the responsivity of the 3D GFET can be further improved to 475.5 A W-1 with a relative fast response speed.4.A self-powered vibration sensor based on 3D GFET has been demonstrated.Inspired by the structure of the non-closed cylindrical cantilever shell,the vibration sensor is designed as a 3D tubular GFET with 3/4 winding.In the self-powered mode,the response of the sensor to vibrating signals with different frequencies and intensities were characterized.Based on the theory of thin-walled cylindrical shell,the finite element model of the sensor is also built,whose working mechanism is investigated through simulation.The research results indicate that the 3D GFET would be applied to measure the vibrations with different frequencies and intensities,based on the piezoelectric effect.In summary,the 3D GFET proposed in this paper could be used as high-performance sensors,which show great application potential in the field of wide broadband,high sensitivity and ultra-fast photodetections,as well as self-powered vibration detections.It has been demonstrated that our 3D GFET show good research value and application prospects,which would provide a new approach for novel and high-performance graphene based sensors.
Keywords/Search Tags:Three-dimensional, Graphene, Field-effect transistor, Photosensor, Vibration sensor
PDF Full Text Request
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