Broad-spectrum and ultrasensitive photodetectors based on GeSe/SnS2 heterostructures with type-III band alignment

Abstract

Two-dimensional (2D) van der Waals heterostructures (vdWHs) show great potential as building blocks for electronic and optoelectronic devices due to their unique band alignments at the contact interface, which can be tailored to achieve specific electronic and optical properties. The most studied 2D vdWHs have type-I and type-II band alignment, while for type-III band alignment vdWHs, carriers are transported through band-to-band tunneling, which have great potential for applications in low-power devices. Herein, we utilize the band structure alignment properties of GeSe and SnS2 to create GeSe/SnS2 vdWHs with type-III band alignment by all-dry transfer process. The GeSe/SnS2 vdWHs demonstrate an intriguing anti-ambipolar behavior attributed to their type-III alignment of electronic band structures. They also exhibit excellent photoresponse properties with broadband photoresponse from ultraviolet C (255 nm) to near-infrared (1920 nm), a competitive detectivity of 1.09 × 1010 Jones, a large responsivity of 50.7 A/W, and a response speed of 2.1 ms, which are superior to the pure GeSe (the spectral range of about 255–808 nm, the responsivity of 20.8 A/W, and τrise ≈ 20 ms), SnS2 (the spectral range of about 255–660 nm, the responsivity of 22 A/W, and τrise ≈ 50 ms), and the reported GeSe/SnS2 vdWHs.