Pressure-dependent current transport in vertical BP/MoS2 heterostructures

van der Waals heterostructures between two-dimensional (2D) materials offer versatile platforms for innovative electrical device architectures and applications. Black phosphorus (BP) and molybdenum disulfide (MoS₂) emerge as promising candidates for heterostructures, owing to their exceptional electronic properties and gate-tunable capabilities. In this work, we study the electrical properties of a vertical BP/MoS₂ heterostructure fabricated onto a SiO₂/Si substrate in a back-gate configuration. We focus on the effect of air pressure, from atmospheric pressure to 10^-4 mbar, and show that best electrical performances are enabled at the lower pressure. The heterostructure exhibits gate-tunable rectifying current-voltage characteristics, with a rectification ratio close to 10³. The rectifying characteristics present a kink in the forward region revealing different conduction mechanisms, namely drift-diffusion and band-to-band tunneling. Furthermore, when used as a transistor, the device shows n-type conduction, high gate modulation with ON/OFF ratio of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msup><mml:mn>10</mml:mn> <mml:mn>6</mml:mn></mml:msup> </mml:mrow> </mml:math> , low off-state current of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msup><mml:mn>10</mml:mn> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>14</mml:mn></mml:mrow> </mml:msup> <mml:mspace></mml:mspace> <mml:mi>A</mml:mi></mml:mrow> </mml:math> and mobility of 1.6 cm² V^-1 s^-1. The results of this work highlight the potential of BP/MoS₂ heterostructures for applications in low-power electronics, high-performance transistors, and sensitive pressure sensors.