Gate-defined Quantum Confinement in few-layer Black Phosphorus Transistor

Black phosphorus is a novel two-dimensional(2D) semiconductor which has attracted considerable research interest due to its tunable band gap and high electron mobility. Here we demonstrate quantum confinement defined by split gate in devices based on few-layer black phosphorus. The tunability of split gate can be illustrated by the fact that a device can be tuned off by split gate alone. In quantum Hall regime, gate-controlled pinching off of quantum Hall states(with filling factor ν = -1, -2, -3, -4) indicates the realization of strong confinement and the potential of manipulation of edge states. The work opens the door for using black phosphorus as platform for electronic and optoelectronic applications.