Exceptional and Anisotropic Transport Properties of Photocarriers in Black Phosphorus

One key challenge in developing postsilicon electronic technology is to find ultrathin channel materials with high charge mobilities and sizable energy band gaps. Graphene can offer extremely high charge mobilities; however, the lack of a band gap presents a significant barrier. Transition metal dichalcogenides possess sizable and thickness-tunable band gaps; however, their charge mobilities are relatively low. Here we show that black phosphorus has room-temperature charge mobilities on the order of 10⁴ cm² V^–1 s^–1, which are about 1 order of magnitude larger than silicon. We also demonstrate strong anisotropic transport in black phosphorus, where the mobilities along the armchair direction are about 1 order of magnitude larger than in the zigzag direction. A photocarrier lifetime as long as 100 ps is also determined. These results illustrate that black phosphorus is a promising candidate for future electronic and optoelectronic applications.