Graphene/Bi₂Se₃ Heterojunction Phototransistor Using Photogating Effect Modulated by Tunable Tunneling Resistance

Tunable Quantum Tunneling through a Graphene/Bi2Se3 Heterointerface for the Hybrid Photodetection Mechanism

“…Although the formation of the native oxidation layer is very fast at the initial stage after exfoliation, , its thickness is known to saturate since the oxidation process is significantly delayed over time due to the interplay between surface exposure and oxygen incorporation . The thickness of the oxidation layer is estimated as ∼2 nm (±0.2 nm). ,,− …”

“…Each step represents the transition point, where the transport mechanism changes and the resistance state switches to different resistance states. The oxidation layer naturally formed on the Bi 2 Se 3 surface is known to act as a tunneling barrier in contact with graphene. ,,− The tunneling resistance is closely related to the potential barrier at the interface and the electronic density of states in graphene and Bi 2 Se 3 . Hence, the shape deformation of the asymmetric tunneling barrier will have a great influence on the tunneling current across the interface.…”

“…Based on the asymmetric tunneling barrier formed at the graphene/Bi 2 Se 3 interface, − we have explored a breakthrough way to improve the photoresponse characteristics of the graphene/Bi 2 Se 3 heterochannel by suppressing the tunneling dark current and injecting the photogenerated carriers. We have found that the tunneling resistance of the graphene/Bi 2 Se 3 heterojunction can be tuned to couple the photogating effect with the photovoltaic effect in the graphene/Bi 2 Se 3 heterochannel.…”

“…Recent studies reported the control over the dark current in graphene-based photodetectors by introducing an interlayer (e.g., h-BN) tunneling barrier with enhanced photodetectivity. − However, the photodetection performance using this method is highly sensitive to the size, thickness, and quality of the interlayer, which makes the fabrication process challenging. As an alternative pathway free from introducing an interlayer, the natural oxidation layer rapidly formed on the surface of topological insulators , in the ambient environment can be utilized as the tunneling barrier. − In particular, the thickness of the oxidation layer of the topological insulators is saturated within a few hours after exfoliation, and the oxidation process is significantly delayed over time so that a uniform oxidation layer can be obtained over the entire surface. , …”