Gate tunable MoS ₂ –black phosphorus heterojunction devices

Heterojunctions are essential building blocks for modern electronic and optoelectronic devices. The recent discovery of two-dimensional semiconductors offers an opportunity to build these heterojunctions with atomic sharp interfaces by van der Waals interaction. Here we fabricated MoS2–black phosphorus (BP) heterojunction devices. Due to the narrow band-gap and unpinned Fermi level of BP, this heterojunction could be tuned to either p–n or n–n by the electrostatic gating. The current rectification behaviors were observed in both p–n and n–n junctions. The current rectification of the MoS2–BP n–n junction was attributed to the energy barrier formed at the interface of wide band-gap MoS2 and narrow band-gap BP. The gate dependence of forward current, reverse current and current rectification properties of the heterojunction at different thickness scale were systematically studied, suggesting the electrical properties of the heterojunction could be controlled by designing the thickness of MoS2 and BP flake.