ORDERING OF AMORPHOUS-SILICON DURING SOLID-PHASE EPITAXY STUDIED BY SCANNING-TUNNELING-MICROSCOPY

The early stages of silicon solid-phase epitaxy (SPE) on the Si(111) s urface are studied by scanning tunneling microscopy(STM). It is shown that an amorphous layer with thickness around two bilayers deposited o n the silicon surface transforms in a polycrystalline layer with extre mely small grain size (about 2-3 nm) after heating to 430 degrees C. T he atomic-resolution STM imaging of such a disordered surface allows u s to extract lateral coordinates of the upper-layer atoms. The applica tion of the pair-distribution-function formalism reveals anisotropy in the orientational order that might indicate that the SPE occurs prefe rably in the step direction.