摘要：As the base of modern electronic industry,field-effect transistor(FET) requires the channel material to have both moderate bandgap and high mobility. The recent progresses indicate that few-layer black phosphorus has suitable bandgap and higher mobility than two-dimensional(2D) MoS_2, but the experimentally achieved maximal mobility(1000 cm^2 V^(-1) s^(-1)) is still obviously lower than those of classical semiconductors(1,400 and 5,400 cm^2 V^(-1) s^(-1) for Si and InP). Here, for the first time, we report on monolayer antimonide phosphorus(SbP) as a promising 2D channel material with suitable direct bandgap, which can satisfy the on/off ratio, and with mobility as high as 10~4 cm^2 V^(-1) s^(-1)based on density functional theory calculation. In particular,α-Sb_(1-x)P_x monolayers possess 0.3–1.6 eV bandgaps when0.1 ≤ x ≤ 1, which are greater than the minimum bandgap(0.4 eV) required for large on/off ratio of FET. Surprisingly,the carrier mobilities of α-Sb_(1-x)P_x monolayers exhibit very high upper limit approaching 2×10~4 cm^2 V^(-1) s^(-1) when 0 ≤x ≤ 0.25 due to the ultra-small effective mass of holes and electrons. This work reveals that 2D SbP with both suitable bandgap and high mobility could be a promising candidate as eco-friendly high-performance FET channel materials avoiding short-channel effect in the post-silicon era, especially when considering the recent experimental success in realizing arsenide phosphorus(AsP) with similar structure.