Modification of interface and electronic transport in van der Waals heterojunctions by UV/O3

Abstract

Two-dimensional (2D) van der Waals heterojunctions have many unique properties, and energy band modulation is central to applying these properties to electronic devices. Taking the 2D graphene/MoS2 heterojunction as a model system, we demonstrate that the band structure can be finely tuned by changing the graphene structure of the 2D heterojunction via ultraviolet/ozone (UV/O3). With increasing UV/O3 exposure time, graphene in the heterojunction has more defect structures. The varied defect levels in graphene modulate the interfacial charge transfer, accordingly the band structure of the heterojunction. And the corresponding performance change of the graphene/MoS2 field effect transistor indicates the shift of the Schottky barrier height after UV/O3 treatment. The result further proves the effective band structure modulation of the graphene/MoS2 heterojunction by UV/O3. This work will be beneficial to both fundamental research and practical applications of 2D van der Waals heterojunction in electronic devices.