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O: Fachverband Oberflächenphysik
O 59: Poster Session II (Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: arrays; Nanostructures at surfaces: Wires, tubes; Nanostructures at surfaces: Other; Plasmonics and nanooptics; Metal substrates: Epitaxy and growth; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsoprtion of organic / bio molecules; Metal substrates: Adsoprtion of inorganic molecules; Metal substrates: Adsoprtion of O and/or H; Metal substrates: Clean surfaces; Density functional theory and beyond for real materials)
O 59.117: Poster
Mittwoch, 24. März 2010, 17:45–20:30, Poster B1
Ab initio study of structural stability of InAs nanowires — •Leila Salimi1, Nahid Ghaderi2, Seyed Javad Hashemifar1, and Hadi Akbarzadeh1 — 1Department of Physics, Isfahan University of Technology, 84156-83111 Isfahan, Iran — 2Theory@Elettra Group, INFM-CNR DEMOCRITOS, c/o Sincrotrone, I-34012 Trieste, Italy
We have studied the structural stability of InAs nanowires with different diameters by using density functional theory - pseudopotential computations. The stable structure of bulk InAs is Zinc Blende (ZB) although under special experimental conditions Wurtzite (WZ) InAs has also been observed. Due to the high symmetry and low ratio of dangling bonds, we have considered hexagonal and triangular WZ nanowires in [0001] direction and hexagonal ZB nanowires in [111] direction. In order to select facets of the nanowires, we calculated formation energy of nonpolar surfaces of both structures and found that ZB(110) and WZ(1010) surfaces are more stable than others. All nanowires were calculated in the optimized and relaxed supercells. Calculating the cohesive energy of nanowires with small diameters, we found WZ structure more stable than ZB, in good agreement with experimental results. The obtained cohesive energy of the small diameter nanowires were fitted by a phenomenological model to obtain dangling bond energies and then extrapolate the cohesive energy of large diameter nanowires. The extrapolated results indicate that for diameters up to 50 Angstrom, the WZ nanowires are more stable than ZB nanowires while for larger diameters, the contribution of dangling bonds reduces and the results converge to that of bulk InAs.