Theoretical investigation of structural and electronic properties of wurtzite GanAsn clusters

We have used the density-functional tight-binding method to study the structural, electronic, and optical properties of stoichiometric wurtzite GanAsn clusters for n upto 105. The results presented include the radial distribution, Mulliken population, electronic energy level, band gap and stability as a function of the size. We suggest that interatomic bonds in the outer region of the clusters are more ionic than those in the interior of the clusters. Both highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are surface states and HOMO-LUMO gap decreases with increasing cluster size. We also present a comparative analysis of the structural and electronic properties of wurtzite clusters with those of zinc-blende clusters.