  Today, 2D semiconductor materials have been extended into the nitrogen group:
phosphorene, arsenene, antimonene and even nitrogene. Motivated by them, based
upon first-principles density functional calculations, we propose a new
two-dimensional phosphorus nitride (PN) structure that is stable well above the
room temperature, due to its extremely high cohesive energy. Unlike
phosphorene, PN structure is resistant to high temperature oxidation. The
structure is predicted to be a semiconductor with a wide, indirect band gap of
2.64 eV. More interestingly, the phosphorus nitride monolayer experiences an
indirect-to-direct band-gap transition at a relatively small tensile strain.
Such dramatic transformation in the electronic structure combined with
structural stability and oxidation resistance at high temperature could pave
the way for exciting innovations in high-speed ultrathin transistors, power
electronic modules, ultra-high efficiency LEDs and semiconductor lasers.
