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 las er ablating a GaAs target in an Ar background gas. X-ray diffraction and tr ansmission electron microscopy revealed that these GaAs nanoclusters had ra ndomly oriented crystalline cores and As-rich amorphous oxide outer shells. These clusters assembled, upon vacuum annealing, along step edges and at d efects on substrates to form wire-like structures. Our results also showed that GaAs films, when deposited in vacuum, did not have crystalline cores a nd were rich in As. Postdeposition annealing in vacuum to between 400 and 5 00 degrees C drove off the excess As. The stoichiometry of the films was co nfirmed by both Auger electron spectroscopy and x-ray photoelectron spectro scopy. (C) 1999 American Institute of Physics. [S0003-6951(99)02441-9].