Does single-layered Aluminium Phosphide exist? I'm currently working with the band structure of graphene and graphene-like compounds.

α-Boron Nitride (hexagonal, single layer) has many interesting properties. I was wondering if the next period analogue, a hexagonal single-layered Aluminium Phosphide existed. Wikipedia lists this compound, but it seems to only be found with a multilayered sphalerite structure.

Does an allotrope of AlP exist (in a stable state at normal conditions) where the structure is similar to graphene or silicene? If not, why?
I suspect that it does not.  As far as I know, all trivalent phosphorous is highly pyramidal--or at least not planar. This would rule out any graphene-like structure.

The reasoning that I have seen is based on hybridization. In the second row (third period) the 3s and 3p atomic orbitals are well separated, implying that s and p can not mix and that the outer valence is unhybridized. If bonding is with unhybridized p's, then bonding would occur at right angles.

(Kutzelnigg, W. Angew. Chem., Int. Ed. Engl. 1984, 23, 272.)

(Brown, E. Organometallics 2000, 19, 2208-2214.)