Attachment–detachment limited kinetics on ultra-flat Si(111) surface under etching with molecular oxygen at elevated temperatures

Abstract

Abstract We have used in situ ultrahigh vacuum reflection electron microscopy to investigate the process of two-dimensional negative islands (etching pits) nucleation on extremely wide (up to 120 μm in diameter) terraces at Si(111) surface during thermal etching with molecular oxygen at temperatures above 1000 °C. By analyzing nucleation kinetics at different temperatures and comparing the results with theoretical model, we determined the dominant surface mass transport mechanism. The squared critical terrace size D crit 2 for nucleation of new island is found to follow power law form with scaling exponent χ changing from 0.95 to 1.15 as the temperature increased T crit = 1180 °C. At temperatures above T crit we estimated the energy of the vacancy–step interaction E AD as 1.5 ± 0.15 eV. We conclude that observed changes of the D crit in high temperature region (above T crit ) can occur through detachment–attachment kinetics of vacancy–step exchange process rather than via surface diffusion.