In situ scanning tunnelling microscopy investigations of Si epitaxial growth on pit-patterned Si (001) substrates

Si growth on pit-patterned Si (001) substrates fabricated by electron beam lithography and reactive ion etching was studied by in situ scanning tunnelling microscopy. After reactive ion etching, the pits have cylindrical shape with vertical side walls, which begins to change from the bottom already after annealing at 740 °C. During Si overgrowth, the pit shape evolves into inverted pyramid-like or into multi-facetted inverted dome-like geometries depending on the growth conditions as well as thickness of the deposited Si layer. High-resolution STM images clearly show that the walls of the pits after overgrowth are composed predominantly of DB-type of steps.