Investigation On The Physical Mechanism And Model Of Novel Terahertz Detector

With the advancement of related technologies based on millimeter wave or infrared ray,applications such as 5G mobile phones,automotive radars,and precise guidance have gradually expanded in life,bringing great improvements in the quality of our lives.However,the technology based on terahertz wave,which is between the millimeter and infrared in the electromagnetic spectrum,is not yet mature.In fact,compared with millimeter wave and infrared technology,terahertz technology has high transmission rate,low photon energy,large bandwidth which makes it possible to further promote the development of 6G communication,security detection,terahertz radiation,molecular detection and other fields.As one of the basic technology of terahertz,terahertz detection technology has also been greatly developed in recent years due to its important applications in many fields such as biomedical imaging,security detection,satellite sensing,and so on.Some detectors that can work in the terahertz band have been proposed by researchers,such as bolometer,Schottky barrier diodes,terahertz detectors based on plasma wave theory(TeraFET),and so forth.Among them,the TeraFET detector has unique advantages in process compatibility,integration,and cost because it is a field-effect transistor-based device and can also be comparable to other types of detector in terms of responsivity and noise equivalent power(NEP),which means this type of terahertz detector has great potential to become one of the most important devices for the development of terahertz detection technology in the future.However,most of the research on TeraFET detectors is based on two-dimensional electron gas(2-DEG)in high electron mobility transistors(HEMTs)or inverse layer carriers in traditional metal-oxide-semiconductor field effect transistors(MOSFETs).However,with the continuous shrinking of MOSFET process nodes and the emergence of multi-gate processes,the metrics of some devices with distributed carrier channel characteristics in the field of terahertz detection cannot be perfectly explained by previous theories.Initially,this paper analyzes the plasma-wave detection theory and responsivity model of terahertz detector.Based on the relationship between responsivity and the parameter ? in nonresonant detection model,this paper proposes a novel terahertz detector based on local high-mobility heterojunction MOSFET.By improving the channel carrier mobility and suppressing the substrate leakage current,the photoresponse is effectively improved by 200%.In addition,a method capable of assisting the analysis of terahertz detectors with three-dimensional distributed carriers is proposed by analyzing and optimizing the subthreshold ideality factor ?.This method makes an excellent prediction of the maximum responsivity of the terahertz detector in non-resonant mode.Based on the proposed method,this paper presents a terahertz detector based on double-gate(DG)MOSFET.Compared with the conventional single-gate(SG)MOSFET terahertz detector,the photoresponse is improved by more than 50%.The error between the maximum photoresponse and the predicted maximum value under different parameters does not exceed 10%,and even in the case of long gate length and thin channel,the error is only 1%.In summary,this paper proposes two new types of terahertz detector structures,which effectively improve the performance of terahertz detectors,and for the first time,an analysis method for distributed carrier detectors is proposed which would play a very important role in terahertz detection.