STRANSKI-KRASTANOV GROWTH OF AG ON AU(111) ELECTRODES

We present results obtained by in situ scanning tunneling microscopy w hich show the morphological details of the transition from layer by la yer growth to three-dimensional island growth during electrodeposition . Two epitaxial layers of Ag are sequentially formed prior to the hete rogeneous nucleation of three-dimensional Ag crystallites which prefer entially develop on steps. The 3D growth initiates when 2D protrusions growing on the completed second adlayer achieve a critical dimension of order 20-50 nm. Our observations and analysis indicate that the gro wth transition may be kinetically determined by adatom migration over descending steps.