A promising two-dimensional channel material: monolayer antimonide phosphorus

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) MoS2, 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, alpha-Sb1-xPx monolayers possess 0.3-1.6 eV bandgaps when 0.1 <= 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 alpha-Sb1-xPx monolayers exhibit very high upper limit approaching 2x10(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.