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

We present results obtained by in situ scanning tunneling microscopy which show the morphological details of the transition from layer by layer growth to three-dimensional island growth during electrodeposition. Two epitaxial layers of Ag are sequentially formed prior to the heterogeneous nucleation of three-dimensional Ag crystallites which preferentially 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 growth transition may be kinetically determined by adatom migration over descending steps.