▎ 摘　　要

Carrier mobility plays a key role in the performance of microelectronic devices, especially the field effect transistors (FET). To design next generation two-dimensional (2D) FET, stable channel materials with a higher carrier mobility than silicon and a significant band gap are highly desirable, but are still not discovered. Here, we report a group of 2D materials of BX (X = P, As, and Sb), which are semiconducting with an ultrahigh carrier mobility. Using first-principles calculations, we find that all BX configurations are similar to graphene, but possess direct bandgaps of 1.36, 1.14, and 0.49 eV, respectively. Based on deformation potential theory, BX monolayers are predicted to have superior mobilities (>10(4) cm(2) V-1 s(-1)) to phosphorene. In particular, the electron mobility of monolayer BSb is 3.2 x 10(5) cm(2) V-1 s(-1), approaching the figure of merit in graphene (similar to 3 x 10(5) cm(2) V-1 s(-1)). These results demonstrate that BX monolayers are of paramount significance for next-generation 2D FET manufacture.