Detection of cyclotron resonance using photo-induced thermionic emission at graphene/MoS₂ van der Waals interface

We demonstrate the detection of cyclotron resonance in graphene by a photo-induced thermionic emission mechanism at the graphene/MoS₂ van der Waals (vdW) Schottky junction. At cyclotron resonance in Landau-quantized graphene, the infrared light is absorbed, and an electron–hole pair is generated. When the energy of a photoexcited electron exceeds the band offset energy at the graphene/MoS₂ interface, the electron transfer occurs from graphene to the conduction band of MoS₂, and the hole remains in graphene. This creates an electron–hole separation at the graphene/MoS₂ interface at cyclotron resonance, and a photovoltage is generated. The proposed method is an infrared photodetection technique through out-of-plane transport at the vdW junction, which is distinct from the previously reported methods that use in-plane transport in graphene for electronic detection of the cyclotron resonance. Despite the simple structure of our device with a single-vdW junction, our method exhibits a very high sensitivity of ∼10⁶ V/W, which shows an improvement of three orders of magnitude over the previously reported values. Therefore, the proposed method displays a high potential for cyclotron resonance-based infrared photodetector applications.