Simulation Of Novel Tunneling Transistors In Terahertz Detection

Terahertz radiation is a high-frequency radiation with good penetration ability and little damage to living bodies.Its wavelength ranges between that of microwave and infrared radiation.The radiation has significant market potential in broadband communication,radar,electronic countermeasures,medical imaging and security inspection.Terahertz detectors,the key device in terahertz imaging,has drawn wide attention.The terahertz detectors with Si-based integrated circuit manufacture process has multiple advantages including working in room temperature,low cost,easy to manufacture and better imaging ability.However,standard CMOS transistors have a reducing response as signal frequency increases,and have difficulty detecting terahertz signals over 1THz.The tunnel field-effect transistor(TFET)with Si-based integrated circuit manufacture process is capable of rectifying high frequency signals thanks to the nonlinearity in its on current--gate voltage relationship.Since the tunneling time of an electron is as short as 10-15s,TFET has a theoretical response quick enough for relatively higher frequency signals.However,traditional PIN-structured TFETs have low on currents and low response to terahertz signals.An innovative TFET structure with increased tunneling area(source-junctionless TFET/SJL TFET)is proposed for terahertz detecting.On a simulation platform built with Silvaco TCAD for the study of the static and dynamic characteristics of Si-based TFET,comparison in static characteristics as well as terahertz response between PINTFET and the novel TFET with increased tunneling area show that:(1)Both SJL TFET and PIN TFET can under certain circumstances achieve a subthreshold swing(SS)below 60mV/dec,which is the SS limit for MOSFET,enabling lower power consumption.SJL TFET has a greater potential in the decrease of SS that reaches as small as 6.24mV/dec.(2)Both SJL TFET and PIN TFET have SS varied with structure parameters and doping profile.The SS decreases with thinner gate oxide and lower doping concentration.The latter also decreases drain current by multiple orders of magnitude.The depth of PN junction has a significant influence on PIN TFET.An optimal set of parameters are determined for PIN TFET as well as SJL TFET:gate oxide thickness Tox 0.8nm,source doping concentration le20cm-3,junction depth 40nm.(3)SJL TFET,PIN TFET and MOSFET are capable of responding to terahertz signals while TFETs have a better voltage response than MOSFET in general,and a slower decrease with increased frequency.SJL TFET has a significant advantage towards traditional PIN TFET in the response at each frequency.(4)The novel SJL TFET terahertz detector is adequate to be a new and important direction in terahertz detectors for its advantage towards tradition PIN TFET and MOSFET in multiple device performance indexes.The optimized TFET structure proposed,with potentially high response to terahertz signals and low power consumption,provides new methods and directions for the study of terahertz detectors.