Growth kinetics of thermal oxidation process on Si(100) by real time ultraviolet photoelectron spectroscopy

Initial thermal oxidation processes by dry oxygen within the first submonolayer on Si(100) have been investigated by real time ultraviolet photoelectron spectroscopy. For oxidation temperatures at 350–600°C the time evolution of the O 2p state intensity, a good measure for the amount of the formed oxide, presented a Langmuir-type adsorption behavior, showing a rapid increase after the introduction of the oxygen followed by a gradual saturation. For temperatures above 700°C, on the other hand, the onset of the oxidation was delayed, and the whole time evolution was well described by a model assuming a two-dimensional island growth. A unified explanation is given for this difference in the oxidation kinetics by considering the presence of the oxide decomposition process in the higher temperature region.