Fig. 1. Structure and characterization of the graphene/MoS₂/h-BN/graphene vertical heterostructure photodetector device; (a) Schematic of the device structure; (b) Corresponding optical microscopy image and AFM characterization of the real fabricated heterostructure device; (c1), (c2) Raman spectra of MoS₂, graphene and h-BN

Fig. 2. Photocurrent characteristics of the graphene/MoS₂/h-BN/graphene vertical heterostructure photodetector device. The I-V characteristics of the device under dark and 532 nm laser illumination with applied (a) negative bias and (b) positive bias; FN tunneling fitting curves of the device under dark and 532 nm laser illumination with applied (c) negative bias and (d) positive bias

Fig. 3. Energy band diagrams of the graphene/MoS₂/h-BN/graphene heterostructure. (a) Energy band diagram of the device with zero bias. (b) Energy band diagrams of the device under dark and 532 nm laser illumination at V_ds < V_N-D-FN; (c) Energy band diagrams of the device under dark and 532 nm laser illumination at V_ds > V_P-D-FN

Fig. 4. Optoelectronic properties of the graphene/MoS₂/h-BN/graphene vertical heterostructure device. (a) The I-V characteristics of the device under dark and 532 nm laser illumination with different power densities; (b) ln(I_ds/V²)–1/V_ds curves of the device under dark and 532 nm laser illumination with different power densities; (c) Power-dependent photocurrent of the device at V_ds = 6.75 V; (d) Responsivity and I_light/I_dark ratio along with illumination intensities

Fig. 5. Comparison of the response time and cyclic stability between graphene/MoS₂/h-BN/graphene vertical heterostructure and graphene/MoS₂ heterostructure devices. (a) The dynamic temporal photoresponse of the graphene/MoS₂/h-BN/graphene heterostructure device with the enlarged current profile between 11 s and 16 s; (b) The dynamic temporal photoresponse of the graphene/MoS₂ heterostructure device with the enlarged current profile between 60 s and 100 s

Table 1. The transition bias and barrier height of the graphene/MoS₂/h-BN/graphene vertical heterostructure photodetector device under 532 nm laser illumination

Table 2. Comparison between the performances of typical vertical heterostructure photodetector devices