REFLECTION ELECTRON-MICROSCOPY METHODOLOGY FOR QUANTIFICATION OF CLUSTER GROWTH - INDIUM CLUSTERS ON THE INP(110) SURFACE

Dynamical reflection electron microscopy (REM) can provide a wealth of time-resolved data pertinent to the initial and intermediate stages o f cluster growth. REM allows one to follow and quantify the size and s hape evolution of individual clusters. Average cluster size and cluste r density data can be obtained as a function of time due to the large field of view produced by REM image foreshortening. We describe here a methodology for extracting these data from dynamical REM experiments, based on a geometrical model for the interpretation of REM images fro m two-and three-dimensional clusters. This methodology has been applie d to studies of In cluster growth on InP(110) surfaces at 650 degrees C. The average In cluster height and length initially increased as a f ourth root of time, with a constant contact angle with the surface, co nsistent with surface-diffusion-limited growth of 3D clusters. The sam e behavior was found in the later stage of cluster growth, but the int ermediate stage showed anomalous power laws for the cluster height and base length, accompanied by a decrease in the contact angle between t he In clusters and the InP(110) surface. This anomalous regime can be explained by growth of In clusters into the InP substrate, when the tr ue contact angle is no longer defined with respect to the InP(110) sur face.