Graphene-Induced Positive Shift Of The Flat Band Voltage In Recessed Gate Algan/Gan Structures

In this work, a layer of graphene is inserted into Al2O3/recessed gate AlGaN/GaN structures to realize the positive shift of flatband voltage V-FB. With a chemically inert surface and a high work function, graphene suppresses the interfacial layer growth, reduces the donor-like interface defects during the growth of Al2O3 gate dielectrics, provides a potential well to confine electrons from AlGaN and the interface defects, lifts the conduction band of GaN, leads to the disappearance of 2DEG at recessed AlGaN/GaN interface, and positively shifts V-FB from 1.4V to 5.2V. This method provides a promising solution to fabricate E-mode AlGaN/GaN high electron mobility transistor.