PREPARATION OF GASB(100) SURFACES BY ULTRAVIOLET-IRRADIATION

The preparation of GaSb(100) surfaces by ultraviolet (UV) irradiation, prior to molecular beam epitaxy (MBE) growth, has been investigated. After optimization of the UV irradiation parameters (type of lamp, dis tance between the lamp and the sample, time exposure), GaSb surfaces p resent no detectable carbon contamination, a stoichiometry close to th e MBE surface one, and a very good morphology. The oxide layers grown an the substrate surface have been analyzed by Auger electron spectros copy and x-ray photoelectron spectroscopy. Large differences in the ox ide composition, resulting from variations of the UV irradiation condi tions, have been observed and analyzed. We discuss the experimental re sults and particularly the carbon desorption, in terms of oxide growth mechanisms and we propose a model of oxide growing in the optimal con ditions. (C) 1997 American Vacuum Society.