High-performance broadband photodetection enabled by a GeP/MoS₂ van der Waals p–n heterostructure

van der Waals (vdW) heterostructures based on two-dimensional (2D) semiconducting materials have been thoroughly investigated for practical applications. Recent studies on 2D materials have reignited interest in p–n junctions, with promising potential for applications in both electronics and optoelectronics. Here, we present a photodiode using a p-type GeP/n-type MoS₂ heterostructure with a strong diode rectification of 2.1 × 10⁴, which confirms the creation of a high-quality p–n junction. The device has a high responsivity of about 754 A W⁻¹ and a high external quantum efficiency (EQE) of about 5.35 × 10⁴ at a bias of 1 V along the source–drain. Photocurrent mapping shows intrinsic photovoltaic behaviour with a photocurrent of 0.39 µA under zero bias conditions, which is enhanced to 0.60 µA under reverse bias conditions and suppressed under forward bias conditions, which provides evidence of junction-dominated carrier separation. The measured photoresponse is sub-linear within a power-law with an exponent α = 0.65, and a stable response of the device with a rise and decay time of 165 milliseconds and 206 milliseconds, respectively, is achieved. These results point to the GeP/MoS₂ vdW heterostructure as a potential platform for high-performance visible light photodetectors with the possibility of extending into the near-infrared region.