Electronic structures and edge effects of Ga₂S₂ nanoribbons

Ab initio density functional theory calculations are carried out to predict the electronic properties and relative stability of gallium sulfide nanoribbons (Ga₂S₂-NRs) with either zigzag- or armchair-terminated edges. It is found that the electronic properties of the nanoribbons are very sensitive to the edge structure. The zigzag nanoribbons (Ga₂S₂-ZNRs) are ferromagnetic (FM) metallic with spin-polarized edge states regardless of the H-passivation, whereas the bare armchair ones (Ga₂S₂-ANRs) are semiconducting with an indirect band gap. This band gap exhibits an oscillation behavior as the width increases and finally converges to a constant value. Similar behavior is also found in H-saturated Ga₂S₂-ANRs, although the band gap converges to a larger value. The relative stabilities of the bare ANRs and ZNRs are investigated by calculating their binding energies. It is found that for a similar width the ANRs are more stable than the ZNRs, and both are more stable than some Ga₂S₂ nanoclusters with stable configurations.