GaAs nanostructures and films deposited by a Cu-vapor laser

The properties of GaAs nanoclusters and films deposited on substrates by a Cu-vapor laser were investigated. Nanoclusters of GaAs were produced by laser ablating a GaAs target in an Ar background gas. X-ray diffraction and transmission electron microscopy revealed that these GaAs nanoclusters had randomly oriented crystalline cores and As-rich amorphous oxide outer shells. These clusters assembled, upon vacuum annealing, along step edges and at defects on substrates to form wire-like structures. Our results also showed that GaAs films, when deposited in vacuum, did not have crystalline cores and were rich in As. Postdeposition annealing in vacuum to between 400 and 500°C drove off the excess As. The stoichiometry of the films was confirmed by both Auger electron spectroscopy and x-ray photoelectron spectroscopy.