Computer modeling and electron microscopy of silicon surfaces irradiated by cluster ion impacts

Multiscale simulation method (MSM) has been used for modeling impacts of Ar clusters, with energies ranging from 20-500eV/atom, impacting Si surfaces. Our simulation predicts that on a Si (100), craters are nearly triangular in cross-section, with the facets directed along the close-packed (111) planes. The Si (100) craters exhibit four-fold symmetry. The craters on Si (111) surface are well rounded in cross-section and the top-view shows a complicated star-like image. The simulation results for Individual gas cluster impacts were compared with experiments at low dose (10¹⁰ ions/cm² charge fluence) for Ar cluster impacts into Si (100) and Si (111) substrate surfaces. Atomic force microscopy (AFM) and cross-sectional high-resolution transmission electron microscope (TEM) imaging of individual gas cluster ion impacts into Si (100) and Si (111) substrate surfaces revealed faceting properties of the craters and are in agreement with the theoretical prediction.