| Terahertz(THz)wave has shown broad application prospects due to its unique spectrum characteristics.In the applications of THz technology,terahertz detectors are an essential part in the realization process.In recent years,Tera FET,also called plasmonic detector,have attracted the attention of researchers for its unique advantages which can operate at room temperature and can be miniaturized.Among Tera FETs,Si CMOS detector has been proven a potential detector for its high-integration and mature process.However,this type detector has a lower responsivity problem compared with HMET Tera FET.In addition to the limit of the mobility of the silicon,it also suffers from parasitism effect and the limit of the channel detection mechanism,resulting an improvement space remaining in responsivity.To investgate the physical mechanism and improve the response of the Si Tera FET detector,this paper firstly investigates the physical mechanism of the Tera FET based on a classical analytical model and illustrates the simulation model and methods of the Tera FET.Based on this,the influence to the response of structure parameters of the Tera FET has been simulated and discussed.Besides,by analyzing the parasitism effect of the Tera FET,a novel stepped doping substrate(SDS)structure have been proposed.The substrate in SDS can suppress the barrier parasitic capacitance and guarantee the sensitive response to the THz signal by a stepped doping strategy.Simulations shows that the SDS can obtain a quarter of parasitic capacitance and an 80% increase of the response.Besides,the further simulations have discussed the related parameters,which provides optimization methods for this detector.In summary,based on the research of the analytical model,this paper has analyzed the structural parameters of the Tera FET,and proposed a novel Tera FET structure,which can suppress the parasitic effect to obtain a high response.And it's meaningful to the optimization of the Tera FET structure. |
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