Current Collapse In Ga₂O₃/GaN Related FET

As a new type of semiconductor material,Ga₂O₃ has wide band gap,high critical breakdown electric field and unique properties in different crystal phases.It has an extremely broad application prospect in the research fields of optoelectronics,high power and high frequency devices.In this Dissertation,the basic characteristics and current collapse of Ga₂O₃/Ga N related FETs have been studied in detail.The obtained results showed that:The density of polarization charge of the heterojunction formed by?-Ga₂O₃ and m-Ga N is 10¹⁴cm^-2,which is one order higher than that of Al Ga N/Ga N heterojunction.The saturation currents of?-Ga₂O₃ HEMTs devices are much larger than that of typical Al Ga N HEMTs.In this paper,the current collapse related to impurity traps in bulk of?-Ga₂O₃/m-Ga N HEMT is studied in detail.The results show that:The trap generated by doping impurity ions doesn't impact the opening and closing of the device,but inhibit the current performance of the device;The device doped with impurity ions will cause current collapse,and the larger drain voltage difference is,the more obvious the current collapse affect;The increase of impurity ion concentration can enhance the current collapse,but the current loss will tend to be flat as the concentration increases to a certain extent.The deep level impurity ions can weaken the current collapse,but the current recovery time is longer than the low level.This Dissertation proposes three methods to suppress the current collapse,namely:compensation doping to suppress the current collapse caused by impurity traps,field plate structure and the new device CAVET to suppress the current collapse caused by surface charges.The study found that after compensating the region on the left side of the m-Ga N buffer of?-Ga₂O₃/m-Ga N HEMT,the current collapse is significantly suppressed,and the drain current can also be increased.The field plate structure can significantly suppress the current collapse caused by surface charges,and the longer the field plate,the more obvious the affect.Due to the vertical structure of CAVET,the electric field is not distributed horizontally but vertically.Therefore,cavet can weaken the surface bound electrons and suppress the current collapse caused by surface charge.