First-principle calculations of the electronic and atomic structures of 2D materials based on aluminum and aluminum nitride

First-principles density functional theory (DFT) calculations were performed to examine the structural, electronic, and bonding properties of Al/AlN 2D structures with cubic and hexagonal symmetries. The results indicate that cubic Al(001)/AlN(001) structures are stable at zero temperature for 1 to 3 layers of Al, while hexagonal Al(111)/AlN(001) structures are unstable for more than one Al layer. In cubic structures, the Al–Al bond lengths can decrease by up to 17%, and Al–N bonds shorten up to 7%, while N–N bonds increase up to 5% when transitioning from bulk to 2D structures. Hexagonal structures also show reduced bond lengths, especially for Al–N and N–N bonds for such transitions. Both types of slabs are metallic, with hexagonal structures exhibiting stronger metallicity. The charge transfer from Al to N reflects the ionic nature of the Al–N bonding in both structures.