基于硅衬底并采用刻槽n+-GaN帽层与局域钝化层的AlGaN/GaN肖特基势垒二极管以提升优值和动态特性

In this work,we design and fabricate AlGaN/GaN-based Schottky barrier diodes(SBDs)on a silicon substrate with a trenched n+-GaN cap layer.With the developed physical models,we find that the n+-GaN cap layer provides more electrons into the AlGaN/GaN channel,which is further confirmed experimentally.When compared with the reference device,this increases the two-dimensional electron gas(2DEG)density by two times and leads to a reduced specific ON-resistance(Ron,sp)of～2.4 mΩ·cm2.We also adopt the trenched n+-GaN structure such that partial of the n+-GaN is removed by using dry etching process to eliminate the surface electrical conduction when the device is set in the off-state.To suppress the surface defects that are caused by the dry etching process,we also deposit Si3N4 layer prior to the deposition of field plate(FP),and we obtain a reduced leakage current of～8×10-5 A·cm-2 and breakdown voltage(BV)of 876 V.The Baliga's figure of merit(BFOM)for the proposed structure is increased to～319 MW·cm-2.Our investigations also find that the pre-deposited Si3N4 layer helps sup-press the electron capture and transport processes,which enables the reduced dynamic Ron,sp.