Nanoscale structural defects in oblique Ar+ sputtered Si(111) surfaces

The present endeavor investigates the controlled surface modifications and evolution of self-assembled nano-dimensional defects on oblique Ar+ sputtered Si(111) surfaces which are important substrates for surface reconstruction. The defect formation started at off-normal incidences of 50 degrees and then deflates into defined defect zones with decrease in oblique incidence, depending strongly on angle of ion incidence. Interestingly, it is observed that mean size & height decreases while average density of these defects increases with decreasing oblique incidence. Non-linear response of roughness of irradiated Si(111) with respect to oblique incidence is observed. Crystalline (c-Si) to amorphous (a-Si) phase transition under oblique argon ion irradiation has been revealed by Raman spectroscopy. Our analysis, thus, shows that high dose argon ion irradiation generates of self-assembled nano-scale defects and surface vacancies & their possible clustering into extended defect zones. Explicitly, ion beam-stimulated mass transport inside the amorphous layers governs the observed defect evolution. This investigation of crystalline (c-Si) coupled with amorphous (a-Si) phases of nano-structured surfaces provides insight into the potential applications in the nano-electronic and optoelectronic devices thus, initiating a new era for fabricating multitude of novel structures.