Black Phosphorus–Monolayer MoS₂ van der Waals Heterojunction p–n Diode

TLDR

Black phosphorus, a monolayer of black phosphorus (phosphorene), exhibits high carrier mobility (~10,000 cm²/Vs) and a ~0.3 eV direct bandgap, enabling p‑type field‑effect transistors and phototransistors with mobilities up to 1,000 cm²/Vs, yet p‑n junctions based on this material have not yet been realized. This work demonstrates a gate‑tunable p‑n diode formed by a van der Waals heterojunction between p‑type black phosphorus and n‑type monolayer MoS₂. The authors fabricated a van der Waals p‑n heterojunction of black phosphorus and monolayer MoS₂ and used a gate electrode to modulate the diode’s electrical characteristics. Under illumination, the ultra‑thin diodes achieve a peak photodetection responsivity of 418 mA/W at 633 nm and an external quantum efficiency of 0.3 %, indicating potential for broadband photodetection and solar energy harvesting.

Abstract

Phosphorene, an elemental 2D material, which is the monolayer of black phosphorus, has been mechanically exfoliated recently. In its bulk form, black phosphorus shows high carrier mobility (~10000 cm2/Vs) and a ~0.3 eV direct bandgap. Well-behaved p-type field-effect transistors with mobilities of up to 1000 cm2/Vs, as well as phototransistors, have been demonstrated on few-layer black phosphorus, showing its promise for electronics and optoelectronics applications due to its high hole mobility and thickness-dependence direct bandgap. However, p-n junctions, the basic building blocks of modern electronic and optoelectronic devices, have not yet been realized based on black phosphorus. In this paper, we demonstrate a gate tunable p-n diode based on a p-type black phosphorus/n-type monolayer MoS2 van der Waals p-n heterojunction. Upon illumination, these ultra-thin p-n diodes show a maximum photodetection responsivity of 418 mA/W at the wavelength of 633 nm, and photovoltaic energy conversion with an external quantum efficiency of 0.3%. These p-n diodes show promise for broadband photodetection and solar energy harvesting.