Ultrahigh‐Sensitive Broadband Photodetectors Based on Dielectric Shielded MoTe₂/Graphene/SnS₂ p–g–n Junctions

Abstract

Photodetectors capable of detecting light in a wide spectrum is central to diversified optoelectronic applications in spectroscopy, remote sensing, imaging and optical communication. [1] Two-dimensional (2D) transition metal dichalcogenides (TMDs) provide a tremendous potential for broadband optoelectronics due to their relatively high mobility, appropriate bandgaps, and flexibility. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In particular, TMD layers of different bandgaps and doping (p or n types) can be stacked together into van der 2D atomic sheets of transition metal dichalcogenides (TMDs) have a tremendous potential for next-generation optoelectronics since they can be stacked layer-by-layer to form van der Waals (vdW) heterostructures. This allows not only bypassing difficulties in heteroepitaxy of lattice-mismatched semiconductors of desired functionalities but also providing a scheme to design new optoelectronics that can surpass the fundamental limitations on their conventional semiconductor counterparts. Herein, a novel 2D h-BN/p-MoTe 2 / graphene/n-SnS 2 /h-BN p-g-n junction, fabricated by a layer-by-layer dry transfer, demonstrates high-sensitivity, broadband photodetection at room temperature. The combination of the MoTe 2 and SnS 2 of complementary bandgaps, and the graphene interlayer provides a unique vdW heterostructure with a vertical built-in electric field for high-efficiency broadband light absorption, exciton dissociation, and carrier transfer. The graphene interlayer plays a critical role in enhancing sensitivity and broadening the spectral range. An optimized device containing 5−7-layer graphene has been achieved and shows an extraordinary responsivity exceeding 2600 A W −1 with fast photoresponse and specific detectivity up to ≈10 13 Jones in the ultraviolet-visible-near-infrared spectrum. This result suggests that the vdW p-g-n junctions containing multiple photoactive TMDs can provide a viable approach toward future ultrahigh-sensitivity and broadband photonic detectors.

2D Metal Chalcogenides for IR Photodetection

“…Analogously, the hybrid heterostructure exhibits a broadband detection ability from ultraviolet to short‐wavelength infrared. Peculiarly, the responsivity and detectivity of the hybrid heterostructure photodetector reach up to 2.64 × 10 3 A W −1 and 1.1 × 10 13 Jones under the illumination of 1064 nm light, respectively . The performance not only exceeds the MoTe 2 /graphene and WSe 2 /graphene/MoS 2 heterostructure but also is superior to the current advanced commercial infrared photodetectors (≈10 12 Jones) requiring cryogenic cooling …”

“…Benefiting by the short transmit distance in the vertical direction, the heterostructure has shown high speed response of 24 µs and recovery of 46 µs processes . In addition, novel sandwich p‐g‐n heterostructures in which graphene acts as the middle photoactive layer and n‐type or p‐type 2DMCs as the top and down transmit layer have also shown excellent detection ability . Long et al have presented WSe 2 /graphene/MoS 2 p‐g‐n van der Waals heterostructure for broadband photodetection with a response range up to 2400 nm .…”

“…Hence, the heterostructure has demonstrated competitive device performance, including a high specific detectivity of 10 11 Jones in the NIR region (Figure b) and an ultrafast photoresponse speed of 53.6/30.3 µs . Very recently, Li et al have fabricated an improved p‐g‐n hybrid heterostructure consisting of 2D h‐BN/p‐MoTe 2 /graphene/n‐SnS 2 /h‐BN, as shown in Figure c . In this structure, h‐BN provides an encapsulation effect to avoid the pernicious impact of the charged from the surroundings contamination or substrate surface on the device performance.…”

“…Inset shows a schematic of the heterostructure. Reproduced with permission . Copyright 2019, Wiley‐VCH.…”

A gate-tunable symmetric bipolar junction transistor fabricatedviafemtosecond laser processing

“…[20][21][22][23][24] One of the most signicant investigations in 2D materials is in van der Waals heterostructure devices. 14 Multifunctional p-n diodes, 25,26 ultrasensitive photodetectors, 27,28 high-performance memories, 29,30 light-emitting diodes, 31 and bipolar junction transistors 32 have been fabricated from these materials, showing their potential application in future nanoelectronics. Although several studies on BJTs based on 2D van der Waals heterostructures can be found in the literature, [33][34][35][36][37][38] these structures have an intricate growth procedure 33,34 and tedious multistep transfer process, [35][36][37] making them difficult to fabricate.…”