Nanostructure formation by O2 + ion sputtering of Si/SiGe heterostructures

Abstract

Arrays of nanoscale depressions were observed during sputtering of Si/SiGe heterostructures using 500 eV O2 + ions at angles of incidence between 46° and 56° with simultaneous sample rotation in a secondary ion mass spectrometry system. Both the atomic force microscope and transmission electron microscope results suggest that these depressions were produced as a result of preferential sputtering of Ge and only occur when there are undulations present at the Si/SiGe interface. Formation of the interface undulation appears to occur in tandem with the increase in the Ge surface segregation at the Si/SiGe interface for layers grown at elevated temperatures.