A Differential Extended-gate AlGaN/GaN HEMT Sensor Is Designed,Fabricated,and Performance Tested

AlGaN/GaN high electron mobility transistors(HEMT)is a third-generation semiconductor gallium nitride(Ga N)-based device that has high carrier concentration and electron mobility,chemical stability,and easy Integration and other advantages have been used in the production of sensors in recent years,and have extensive application prospects in important areas such as modern food safety,medical health and environmental protection.Among them,the AlGaN/GaN HEMT sensor with extended gate structure has proven to have certain advantages.However,due to the influence of environmental noise factors in the actual operation process,the accuracy of the experimental results of traditional extended-gate AlGaN/GaN HEMT sensors will be affected.Therefore,starting from this problem,this paper proposes,designs and prepares an AlGaN/GaN HEMT sensor combining extended gate structure and differential design,and studies the surface modification and performance test of the sensor's sensing area.Specific research contents include:1.Based on the analysis of the structure and working principle of the traditional extended-gate AlGaN/GaN HEMT sensor,the paper incorporates the concept of differential design into it,and constructs two identical detection units(measurement unit and reference unit)for detection.Target substances and eliminate environmental noise signals.Based on the theoretical analysis of the relationship between the sourcedrain current of the sensor,the structure of the transconductance and the sensing area,and the feasibility of micro-nano processing,the specific structural parameters of the sensor were designed.2.Complete the fabrication of the differential extended gate AlGaN/GaN HEMT sensor through micro-nano processing processes such as pretreatment,mesa isolation,ohmic contact,lead electrode fabrication,extended gate fabrication,and PDMS packaging.Combined with the electrochemical method,2-mercaptosuccinic acid can effectively react with gold nanoparticles(Au NPs)on the sensor sensing surface to form Au-S bonds and show a good specific complexation reaction to iron ions.This is to testthe performance of the sensor.The sensing surface of the measurement unit in the two detection units of the sensor is modified with 2-mercaptosuccinic acid,while the reference unit is not modified.3.The complex reaction between 2-mercaptosuccinic acid on the surface of the extended cell of the measurement unit and different concentrations of iron ions causes a point change on the surface of the extended cell of the measurement unit,which changes the source and drain current,while the reference cell has no Modification,which is only affected by noise factors,is regarded as an environmental noise signal.Therefore,the output of the reference unit can be used to eliminate the output of the reference unit to obtain more accurate experimental results.Experimental results show that the sensor can effectively reduce the influence of noise factors compared with ordinary extended-gate AlGaN/GaN HEMT sensors,lower the detection limit to 10 f M,and improve the order of magnitude.It also has a larger detection range,10 f M-100 ?M.The research shows that this novel and unique differential extended gate design can overcome the shortcomings of ordinary extended gate AlGaN/GaN HEMT sensors and significantly improve the overall performance of AlGaN/GaN HEMT sensors.