Electrical and Optoelectronic Characterization of Van der Waals BP/MoS₂ Heterostructures for innovative photodetectors and for quantum technologies

In recent years, heterojunctions formed by stacking two-dimensional (2D) materials have attracted considerable interest because of their outstanding electronic and optoelectronic characteristics. These have paved the way for new device structures and uses. The combination of black phosphorus (BP) and molybdenum disulfide (MoS₂) is particularly noteworthy for its potential in creating state-of-the-art optoelectronic devices. This research explores the dynamics between BP, MoS₂, and chromium (Cr) contacts, shedding light on the electrical characteristics of a BP/MoS₂ heterojunction that exhibits rectifying behavior, mainly n-type conduction, and a significant ON/OFF current ratio. The higher unexpected current observed in the presence of a negative bias applied to both the MoS₂ and BP sides is clarified through an energy band model that includes a type II heterojunction at the BP/MoS₂ interface. In this case, Cr makes a Schottky contact with MoS₂ and an ohmic contact with BP. The BP/MoS₂ heterojunction also shows a remarkable photoresponse, which increases linearly with the incident light power, reaching a responsivity of 100 µA/W to white light with an incident power of 50 µW. Time-resolved photocurrent experiments show a fast response, with rise times of less than 200 milliseconds. Moreover, the rectifying characteristics at lower pressure present a kink in the forward region revealing different conduction mechanisms, namely drift-diffusion and band-to-band tunnelling. The results of this work highlight the potential of BP/MoS2 heterostructures for applications in low-power electronics, high-performance transistors, photodetector, and sensitive pressure sensors [1,2,3].

[1] Viscardi, L.; et al., Dominant N-Type Conduction and Fast Photoresponse in BP/MoS₂ Heterostructures. Surfaces and Interfaces 2024, 49, 104445.
[2] Di Bartolomeo, A.; et al., Gated BP/MoS₂ heterostructure with temperature enhanced photocurrent. IEEE 24th International Conference on Nanotechnology (NANO) (2024).
[3] Durante, O.; et al., Pressure-Dependent Current Transport in vertical BP/MoS₂ heterostructures. Submitted on 2D Materials.