Study On Performance Of TeraFETs Detector Based On Mixed-mode Simulation

As plasma field effect transistors(TeraFETs)operating in the THz frequency range,they have been widely used in THz detection,mixing,and imaging.Responsivity and Noise Equivalent Power(NEP)are key parameters to measure the performance of TeraFETs detectors,which are worthy of research and improvement to improve the performance of TeraFETs detectors.Compact model and Numerical model play a vital role in the application of terahertz technology.Therefore,the establishment of effective and efficient models to promote the research and application of TeraFETs is of great significance to the scientific community.Based on the Dyakonov-Shur instability principle,the two-dimensional electron gas(2-DEG)of TeraFETs can be used as a resonant cavity to detect terahertz radiation signals.Devices such as AlGaAs/InGaAs HEMTs,AlGaN/GaN HEMTs,Si MOSFETs as TeraFETs detectors apply the above principles well.Compared with AlGaAs/InGaAs HEMTs and Si MOSFETs,due to the spontaneous polarization and piezoelectric polarization of wurtzite materials,AlGaN/GaN HEMT(Conventional HEMT)has higher carrier mobility and 2-DEG density,which has better performance of terahertz detectors at room temperature.However,there are some problems in the current research of TeraFETs detectors,including that the numerical simulation method based on the drift diffusion model cannot accurately describe the unbalanced carrier transport.The research on the device structure that reduces the noise equivalent power of the detector is not deep enough.The existing analytical model cannot accurately characterize the saturation phenomenon of the TeraFETs detector under the large dynamic range of THz radiation signal intensity in the experimental data.Therefore,based on the TCAD platform to study the two-dimensional numerical model of the Conventional HEMT detector,the hydrodynamic model can better simulate the effect of electrons turning into hot electrons and the overshoot effect of electron drift velocity due to electronic inertia.It is necessary to explore new TeraFETs device structure with high responsivity and low noise equivalent power.At the same time,it is also necessary to establish a SPICE model of TeraFETs detector under a large dynamic range of THz radiation signal intensity.In response to the above problems,the main contributions of this paper are the following three aspects.Firstly,a TeraFET detector structure based on AlGaN/GaN-based Recessed-Gate HEMT is proposed.With the higher transconductance of the Recessed-Gate HEMT device,it can provide better channel gate control capability to improve the response sensitivity of TeraFETs detectors.Secondly,a numerical simulation model of the TeraFETs detector was built in Sentaurus TCAD to explore the optimized detection response sensitivity of the Recessed-Gate HEMT detector in the non-resonant mode(?<2?×1 THz)and low intensity THz radiation signal(U_a=0.001 V).The simulation verification of the response saturation of the experimental data of TeraFETs detector in the range of large dynamic THz radiation intensity(0.001 V<U_a<7 V)is carried out.Based on the drift diffusion model and the hydrodynamic model,the Conventional HEMT and Recessed-Gate HEMT device structures were modeled and simulated.The DC simulation results showed that compared with the drift diffusion model,the hydrodynamic model and the experimental data showed better consistency.Next,the numerical simulation model of the TeraFETs detector was established and the transient simulation is performed.The simulation results of its response characteristics are in good agreement with the experimental measurement results and theoretical calculation results under normalized conditions.At the same time,the hydrodynamic model also describes the response saturation of the experimental data of TeraFETs detector in a large dynamic range of THz radiation intensity.And the simulation results show that the responsivity of the Recessed-Gate HEMT detector reaches 4.7 KV/W,and the noise equivalent power is as low as 60 p W/Hz^0.5 under the same gate length,the frequency is 0.9 THz and the THz radiation intensity is 0.001 V.Compared with the performance of the Conventional HEMT detector,the results show that the responsivity of Recessed-Gate HEMT detector is 1.3 times that of Conventional HEMT detector,that is,Recessed-Gate HEMT detector has better THz detection performance.Finally,based on the ADS simulation platform,a compact model of the TeraFETs detector is established.The response saturation under the large dynamic radiation signal is considered in the non-resonant mode(?<2?×1 THz)and large dynamic THz radiation intensity(0.001V<U_a<7 V).The TeraFETs SPICE model of the Conventional HEMT device is established through the lumped RLC circuit structure.The model takes into account the electronic inertia and leakage current to simulate the response voltage saturation in the experimental measurement results.The SPICE model parameters are extracted from the DC experimental data of TeraFETs,and the model is verified.Through simulation,the DC characteristics of the SPICE model are basically consistent with the experimental data.Next,the SPICE model of the TeraFETs is established and transient simulation is performed.The simulation results of its response characteristics are in good agreement with the experimental measurement results and theoretical calculation results under normalized conditions.At the same time,when the frequency is 0.9 THz and under the large dynamic THz radiation intensity range,the response characteristics are simulated based on the SPICE model.It is found that,compared with the theoretical analysis result and the simulation result without considering the leakage current,the simulation result considering the leakage current better simulates the response saturation under the high intensity THz radiation signal in the experiment.