High quality sandwiched black phosphorus heterostructure and its quantum oscillations

TL;DR

This paper reports the fabrication of stable BN-BP-BN heterostructures that significantly enhance black phosphorus mobility and enable observation of quantum oscillations, overcoming environmental degradation issues.

Contribution

The study introduces a novel encapsulation method with hexagonal boron nitride to improve black phosphorus stability and electronic performance.

Findings

Record-high room-temperature mobility of ~1350 cm2/Vs.

Observation of quantum oscillations in BP at low magnetic fields.

BN encapsulation prevents BP degradation in ambient conditions.

Abstract

Two-dimensional (2D) materials, such as graphene and transition metal dichalcogenides have attracted great attention because of the rich physics and potential applications in next-generation nano-sized electronic devices. Recently, atomically thin black phosphorus (BP) has become a new member of the 2D materials family with high theoretical mobility and tunable bandgap structure. However, degradation of properties under atmospheric conditions and high-density charge traps in BP have largely limited its mobility (~400 cm2/Vs at room temperature) and thus restricted its future applications. Here, we report the fabrication of stable BN-BP-BN heterostructures by encapsulating atomically thin BP between hexagonal boron nitride (BN) layers to realize ultraclean BN-BP interfaces which allow a record-high field-effect mobility ~1350 cm2/Vs at room temperature and on-off ratios over 10^5. At low temperatures, the mobility reaches ~2700 cm2/Vs and quantum oscillations in BP 2D hole gas are observed at low magnetic fields. Importantly, the BN-BP-BN heterostructure can effectively avoid the quality degradation of BP in ambient condition.