Simulation And Mechanism Study Of Doping Effect On TFET Performance

With the rapid development of integrated circuits,the integration of chips is constantly improving.The feature size of integrated circuit devices is constantly decreasing.The performance of MOSFET gradually cannot meet the demand of integrated circuits.The development of MOSFET is severely restricted.At the same time,the contradiction between chip power consumption and performance has become increasingly significant.To solve the contradiction between chip power consumption and performance,TFET has gradually attracted attention.Compared with MOSFET,the working principle of TFET is the band-toband tunneling effect of carriers.The sub-threshold swing of TFET can break through the60 m V/dec at room temperature.It can achieve a large current at a very low voltage.Therefore,TFET can work normally at very low supply voltage.It is regarded as one of the devices that can replace MOSFET.It has become a hot topic to analyze the working mechanism,explore the key technology and improve the performance of TFET.Doping is widely used in device fabrication as an effective method to improve device performance.However,further research is needed on the effect of doping on the performance of devices,especially TFET.Therefore,in this thesis,the influence of doping on TFET devices is studied in detail.In this thesis,doping in different regions and different types are studied,and the reasons for the results are analyzed from the mechanism.In this thesis,we find out how to set doping to make the subthreshold swing of TFET lower,the off-state current smaller,the on-state current larger,and the ambipolar effect suppressed.The specific research contents are as follows:1.This thesis focuses on how to improve the performance of TFET devices by doping in the source region.The lateral diffusion effect of doped particles in the source region can change the on-state characteristics of TFET.By analyzing the influence of the lateral diffusion of impurity particles in the source region on the performance of the TFET,it is known that when the lateral diffusion range of the impurity is small,the on-state current of the TFET will increase.The on-state characteristics of the TFET are further improved by changing the doping concentration of the source region.Under the condition of ensuring the cost and normal operation of the TFET,increasing the doping concentration of the source region can effectively increase the on-state current of the TFET.By changing the position of the peak doping concentration in the source region,this thesis analyzes the influence of the longitudinal distribution of impurity particles on the tunneling effect of TFET.It's known that the expansion of the tunneling area will increase the tunneling current in a certain situation.The peak position of the doping concentration near the surface of the source region will improve the performance of the TFET better.2.To improve the off-state characteristics and ambipolar effect of TFET,this thesis studies the doping of the drain region of TFET.By discussing the mechanism of off-state current and bipolar effect,this thesis analyzes the influence of impurity distribution on SRH generation rate,electric field,tunneling probability,and the current density of TFET.Under the condition of ensuring the normal operation of the TFET,it's known that appropriately reducing the lateral diffusion range of doped particles in the drain region,reducing the drain region doping concentration,and making the peak position of the drain region doping concentration close to the surface of the drain region can improve the off-state characteristics and ambipolar effect of TFET.It can improve the performance of TFET.3.Based on the above conclusions,to further improve the performance of the structureoptimized TFET,the doping of the device is optimized.The doping of the source region and the drain region is optimized.It enables the device to achieve the goals of low off-state current,low on-state voltage,high on-state current,and low subthreshold swing compared with ordinary devices.It effectively suppresses the ambipolar effect of TFET.