JOURNAL OF APPLIED PHYSICS 102, 054308 (2007)

Annealing of nanostructured silver films produced by supersonic
deposition of nanoparticles

Chong Huang, Michael F. Becker, John W. Keto, and Desiderio Kovar^a)
Center for Nano & Molecular Science and Technology and Texas Materials Institute,
The University of Texas at Austin, Austin, Texas 78712

(Received 28 February 2007; accepted 18 July 2007)


Silver nanostructured films were produced by supersonic jet deposition of nanoparticles generated
by laser ablation of microparticle aerosols (LAMA). The nano- and microscale morphologies of
films were investigated and the electrical conductivities of films were measured in the as-deposited
state and after annealing at temperatures from 100 to 400 °C. Scanning electron microscopy (SEM)
and x-ray diffraction (XRD) were used to analyze the film morphologies and the grain sizes within
the films. These analyses showed that the as-deposited grain size was 14–24 nm and the relative film
densities ranged from 60% to 80%, depending on processing conditions. As a result of the extremely
fine grain size and the lack of organics present on the surface of the grains within the films, the
annealing temperatures required to achieve reasonable conductivities (20%−50% of bulk) were
reduced dramatically compared to films produced from suspensions. For example, the grain size in
the films began to increase at annealing temperatures of as low as 100 °C, and the corresponding
conductivity was greater than 25% of the conductivity of bulk silver. Increases in annealing
temperature resulted in greater coarsening and further increases in conductivity. Calculations
showed that increases in conductivity during annealing at temperatures less than 400 °C resulted
primarily from grain size coarsening rather than densification. © 2007 American Institute of
Physics.#DOI: 10.1063/1.2776163$© 2007 American Institute of Physics.