Study On The New Structure Of Ga N Terahertz Schottky Diode

With the increasing use of electromagnetic radiation,terahertz technology has been gained more and more researchers'attention in recent years.At present,the focus of terahertz technology research is to improve the performance of terahertz radiation sources and detectors.Schottky diodes are often used as detectors and mixers in terahertz detectors due to their fast speed,room temperature operation and easy system integration.Although the traditional GaAs Schottky diode can reach the terahertz band,but the output power is too low,become a bottleneck in the development of terahertz technology.The gallium nitride(GaN)material is a new generation of wide band gap semiconductor material star,with high power advantage to become a hot spot.Therefore,the study of GaN-based Schottky diodes is of great significance to the development of terahertz technology.In the traditional SBD device structure,since the GaN electron mobility is obviously lower than GaAs,so it is very difficult to reduce the total resistance R_S of SBD by the process,resulting in a GaN-based SBD maximum cutoff frequency significantly lower than a GaAs-based SBD.Therefore,we must adopt the new device structure to improve the cut-off frequency of GaN-based SBD.The focus of this paper is Schottky diodes based on AlGaN/GaN heterojunction multi-channel structure.The introduction of AlGaN/GaN heterojunction into GaN SBD can reduce the channel resistance and increase the cutoff frequency of the diode by utilizing the high electron mobility in the two-dimensional electron gas.Heterogeneous multi-channel structure is to add multiple heterojunction to the GaN SBD,making the performance of the diode to further enhance.In this paper,we mainly simulate different GaN-based SBDs.This paper mainly studies various GaN-based SBD,the basic work as follows:First,the static characteristics,reverse breakdown voltage and cutoff frequency of Schottky diodes based on GaN materials,AlGaN materials and AlGaN/GaN heterojunctions were studied.The following conclusions are drawn from the analysis:Doping can improve the forward current of the GaN-based SBD,but will reduce the electron mobility(electron mobility in GaN material is much smaller than GaAs),so we need to find a new way to reduce the resistance;The reason why AlGaN SBD forward current is much smaller than GaN SBD is,the electron affinity of AlGaN material is much smaller than GaN,resulting in a high Schottky barrier;By reducing the Al composition in AlGaN SBD,it is possible to reduce the opening voltage and increase the forward current;Compared with AlGaN SBD,a single AlGaN/GaN heterojunction SBD has a smaller on-resistance;Furthermore,the presence of the heterojunction interface charge causes the diode reverse breakdown voltage decreases.The cutoff frequencies of the traditional structure GaN Schottky diodes and the AlGaN/GaN single heterojunction Schottky diodes are calculated respectively.It is concluded that the heterojunction structure can reduce the series resistance and improve the cutoff frequency of the diode.Then further study the static DC characteristics of the AlGaN/GaN heterojunction multi-channel SBD.The effects of AlGaN/GaN heterojunction polychannel SBD channel change,the change of Al layer of barrier layer,the change of barrier layer and channel layer thickness on the DC characteristics of AlGaN/GaN heterojunction are studied comprehensively.Then,the cutoff frequency of AlGaN/GaN heterojunction multi-channel SBD is calculated by extracting the series resistance of heterogeneous junction multi-channel SBD using the previously simulated IV curve.It is calculated that the series resistance of the heterojunction multi-channel SBD is decreased compared with the GaN Schottky diode of the conventional structure,and the cutoff frequency of the diode is obviously improved.Based on previous research and then,the parameters of AlGaN/GaN heterojunction multi-channel SBD and the suggestions for structural improvement are summarized,the concept of polarization doping is introduced.The possibility of increasing the reverse breakdown voltage to reduce the opening voltage based on the bimetallic anode structure in AlGaN/GaN heterojunction FESBD is introduced into the AlGaN/GaN heterojunction multi-channel SBD.Finally,a manufacturing process of terahertz Schottky diodes based on AlGaN/GaN heterojunction multi-channel structure is presented.