Research On The Model Of Liquid Gate Graphene Field Effect Transistor

With the rapid development of modern technology,people's quality of life has been greatly improved.However,more than 10,000 people are diagnosed with cancer every day in my country,and 7.5 people are diagnosed with cancer every minute,and the data is continuing to rise.Cancer is seriously threatening us.For a variety of cancers,it is necessary to accurately and rapidly detect certain biomolecules in cancer patients,so as to determine the severity of the patient and implement corresponding strategies.Common detection substances such as circulating tumor cells(CTC),exosomes,etc.The concentration of these in blood is very low,so a biosensor with high sensitivity,high selectivity and fast detection speed is required.Nanofield-effect transistors are a new type of biosensors based on nanomaterials,which have attracted the attention of life science and circuit fields due to their unique physicochemical properties,rather high sensitivity,high selectivity,rapid detection,simple operation,and easy integration.wide attention.Graphene is a two-dimensional material with large body-to-surface ratio,high electron mobility,excellent thermoelectric conductivity,and high mechanical strength.Therefore,the biosensor composed of graphene has unique advantages in detecting biomolecules.In this thesis,a liquid-gate graphene field-effect transistor(LG-GFET)is studied,which can dissolve biomolecules because the gate dielectric is an electrolyte solution,which is convenient for biological detection.Using this transistor,the concentration of a series of exosome solutions was detected,and an improved current model was established.The current current models are all established for GFET,and the application of this model to biological detection can only do electrical simulation,and cannot combine some parameters of biological detection to obtain the purpose of biological detection.This thesis firstly corrects based on the traditional GFET current model.The electric double layer capacitance theory is introduced,and the gate capacitance model in the traditional current model is modified.In addition,based on the carrier mobility scattering problem caused by the vertical electric field of the traditional field effect transistor,the carrier migration of the graphene field effect transistor is corrected.to further improve the accuracy of the model.On this basis,this thesis improves the current model from two aspects: on the one hand,the concentration of the test substance is used as the dependent variable,so that the model can represent the direct relationship between the concentration of the test substance and the current,so that the concentration of the test substance can be directly obtained by calculating the measured current.Therefore,in this thesis,the influence of the concentration of the detection substance on graphene doping and the influence of the carrier mobility are studied.Using the principle of chemical equilibrium reaction and the relaxation time function,the relationship model between concentration and doping amount and the relationship between concentration and mobility are established.relational model.On the other hand,using time as the dependent variable enables the model to represent the relationship between current and time,so that the current in a stable state can be obtained from the current detected at any time.In the past,it was only possible to wait for the current to be in a stable state before reading the measured value.It is a way for biological detection to improve the detection rate.Finally,the test results of different concentrations of exosome solutions detected by LG-FET and a series of simulation data of T-CAD-based simulation software were used to verify the accuracy of the model.