The formation of supported monodisperse Au nanoparticles by UV/ozone oxidation process

The influence of surface preparation of GaAs (1 0 0)- and (1 1 l)B-oriented substrates on the self-assembly of Au nanoparticles has been investigated. It has been shown that an UV/ozone surface oxidation process, applied prior to the deposition of a thin Au film, enables the formation of well-distributed Au particles that are very uniform in size. Particles of 4.5 plus/minus 1.4 nm diameter have been obtained by the appropriate heat treatment of a 1-nm-thick Au film. The general applicability of this approach has been demonstrated by reproducing the results on a Si (1 1 1) substrate. The process therefore yielded comparable results independent of the surface orientation. Possible operative mechanisms are discussed including Ostwald ripening, particle migration and coalescence, and Coulomb repulsion of the Au deposition.