Etching Kinetics of Si(111) Surface by Selenium Molecular Beam

Using in situ ultrahigh vacuum reflection electron microscopy, three modes of the etching kinetics of the Si(111) surface with a selenium molecular beam are revealed. In the low temperature region (less than or similar to 650 degrees C depending on the Se deposition rate), the etching kinetics is limited by the energy of formation and desorption of SiSe2 molecules and the surface is completely covered by an impurity-induced silicon selenide phase "1 x 1"-Se. In the temperature range similar to 700-1100 degrees C the etching rate is limited by the amount of Se deposition flow and does not depend on the temperature, surface structure, and etching mechanism (step-layer or two dimensional-island). At high temperatures (greater than or similar to 1150 degrees C), the sublimation of Si atoms begins to make the main contribution to the silicon flux from the surface. A theoretical model describing the temperature and kinetics of transitions between etching modes is formulated.