The structure and electronic properties of (GaAs) and Al/In-doped (GaAs) (n= 2–20) clusters

First principles study of the small (GaAs)n and Al/In-doped (GaAs)n clusters is performed to investigate the changes in structural and electronic properties, when the number of atoms increases and doping with Al/In atoms to the corresponding pristine clusters. The results show that the lowest-energy structures undergo a structural change from two-dimensional to three-dimensional right at n = 4. With the increase of cluster size (n>6), the (GaAs)n clusters tend to adopt cage-like structures, which can be considered as being built from Ga2As2 and six-membered rings with Ga–As bond alternative arrangement. For the larger species, there is a competition between fullerenes built from hexagons and rhombi. The HOMO–LUMO gaps of those optimized gallium arsenide clusters do not show perfect even/odd oscillation, oscillation breaks at n = 12. Addition of small amounts of aluminum to GaAs raises the gap while addition of small amounts of indium to GaAs lowers the gap.