Synergistic effect of covalent functionalization and intrinsic electric field on β-Ga2O3/graphene heterostructures

Abstract

β-Ga2O3/graphene heterostructure engineering has been regarded as an effective method to improve the optoelectronic performance of the β-Ga2O3 device. Here, hydrogenation/fluorination covalent functionalized graphene (HC/FC) was employed, and the synergistic effect of covalent functionalization and intrinsic electric field (Ein) was introduced to further improve and understand the interfacial properties of the heterostructure. Under the covalent functionalization, type-II band alignment with UV-infrared dual-band absorption was found for β-Ga2O3/HC heterostructure, while reserved type-II band alignment with hole doping was realized for p-type β-Ga2O3/FC heterostructure. Upon introducing the synergistic effect of covalent functionalization and Ein for β-Ga2O3/hydro-fluorinated graphene (HCF) heterostructure, except for the above similar characters, both the band offsets and optical absorption are further enhanced in β-Ga2O3/HCF heterostructures. When the direction of intrinsic Ein points to the contact interface, the Fermi level of β-Ga2O3/F-HCF was much closer to the valence band of β-Ga2O3. It was thought that the synergistic effect of covalent functionalization and Ein was more beneficial to promote the application of p-type β-Ga2O3. These findings were deeply revealed by the band levels, electrostatic potential, and charge transfer introduced. Our results were expected to provide useful insight into the synergistic effect of covalent functionalization and intrinsic Ein as well as to enhance the application potential of β-Ga2O3/graphene-based optoelectronic devices.