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 sub monolayer on Si(100) have been investigated by real time ultraviolet p hotoelectron spectroscopy. For oxidation temperatures at 350-600 degre es C the time evolution of the O 2p state intensity, a good measure fo r the amount of the formed oxide, presented a Langmuir-type adsorption behavior, showing a rapid increase after the introduction of the oxyg en followed by a gradual saturation. For temperatures above 700 degree s C, on the other hand, the onset of the oxidation was delayed, and th e whole time evolution was well described by a model assuming a two-di mensional island growth. A unified explanation is given for this diffe rence in the oxidation kinetics by considering the presence of the oxi de decomposition process in the higher temperature region.