Large tunneling photo-thermoelectric voltage using cyclotron resonance in bilayer graphene/MoS₂/monolayer graphene van der Waals tunnel junction

Abstract A tunnel junction using graphene in quantum Hall states (QHS) recently demonstrated the tunneling photo-thermoelectric effect (TPTE), generating a photovoltage under mid-infrared irradiation. Here, we investigate TPTE in a bilayer graphene (BLG)/6-layer MoS 2 /monolayer graphene (MLG) tunnel junction. The MoS 2 layer facilitated the tuning of the resistance-area product RA of the tunnel junction with the gate voltage, which was challenging with the previously used h -BN barrier. The photovoltage responsivity R v due to TPTE increased with increasing RA , and achieved a maximum responsivity R v of 2.5 × 10 6 V W −1 at T = 2 K, which was substantially higher than earlier reports. In a device exhibiting high R v and RA , TPTE voltage was generated when the MLG was in the QHS, in contrast to the low R v and RA device, where TPTE voltage appeared at the boundary between the QHS and non-QHS. These findings provide insights into the TPTE effect for exploring the mid-infrared properties of 2D materials.