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

beta-Ga2O3/graphene heterostructure engineering has been regarded as an effective method to improve the optoelectronic performance of the beta-Ga2O3 device. Here, hydrogenation/fluorination covalent functionalized graphene (HC/FC) was employed, and the synergistic effect of covalent functionalization and intrinsic electric field (E-in) 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 beta-Ga2O3/HC heterostructure, while reserved type-II band alignment with hole doping was realized for p-type beta-Ga2O3/FC heterostructure. Upon introducing the synergistic effect of covalent functionalization and E-in for beta-Ga2O3/hydro-fluorinated graphene (HCF) heterostructure, except for the above similar characters, both the band offsets and optical absorption are further enhanced in beta-Ga2O3/HCF heterostructures. When the direction of intrinsic E-in points to the contact interface, the Fermi level of beta-Ga2O3/F-HCF was much closer to the valence band of beta-Ga2O3. It was thought that the synergistic effect of covalent functionalization and E-in was more beneficial to promote the application of p-type beta-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 E-in as well as to enhance the application potential of beta-Ga2O3/graphene-based optoelectronic devices.