Abstract
The discovery of stable two-dimensional, earth-abundant, semiconducting materials is of great
interest and may impact future electronic technologies. By combining global structural prediction
and first-principles calculations, we have theoretically discovered several previously unknown
semiconducting silicon phosphides (SixPy) monolayers, which could be formed stably at the stoichiometries
of y/x1. Unexpectedly, some of these compounds, i.e., P-6m2 Si1P1 and Pm Si1P2,
have comparable or even lower formation enthalpies than their previously known bulk allotropes.
The band gaps (Eg) of SixPy compounds can be dramatically tuned in an extremely wide range
(0< Eg < 3 eV) by simply changing the number of layers or applying an in-plane strain. Moreover,
we find that carrier doping can drive the ground state of C2/m Si1P3 from a nonmagnetic state
into a robust half-metallic spin-polarized state, originating from its unique valence band structure,
which can extend the use of Si-related compounds for spintronics.
