Ultraviolet Laser-induced Oxidation of Antimony: Chemical Composition and Growth Kinetics of the Oxide Layer

The effects of UV (193 nm) laser irradiation of ant imony in the atmosphere on the kinetics of oxidation and on the oxide stoichiometry have been studied using a quartz microbalance and X-ray photoelectron spectroscopy. An absolute calibration of the quartz microbalance enables us to measure quantitatively the kinetics of the oxygen uptake on a thin film; while XPS results indicate the evolution of the superficial chemical composition of the oxide layer grown on single crystals. At sufficiently low fluence to prevent any thermal effect (_< 3 m J / c m 2) we observe a sharp increase of the oxidation rate and the laser grown oxide layer contains more Sb203 than the native or the thermal oxides. We show that the oxidation is enhanced at low fluence mainly by a mechanism involving electronic excitations into the oxide layer, or of the adsorbed molecules, but not by an optical excitation of the molecules in the gaseous phase.