MODIFICATION OF GASB(100) SURFACES INDUCED BY ANNEALING UNDER VACUUM AND UNDER SB-4 AND AS-4 FLUX

We present Auger and RHEED studies of the modifications of GaSb(100) m olecular beam epitaxy (MBE) surfaces induced by annealing, under vacuu m and under Sb-4 or As-4 flux. After annealing under vacuum, in the 25 0-400 degrees C temperature range, Auger peaks and RHEED intensity sho w modifications of the atoms arrangements and concentrations in the su rface layer. Above 400-420 degrees C Sb desorption results in noticeab le changes of the surface stoichiometry and structure characterized, f or T>500 degrees C, by the formation of Ga droplets. Under normal grow th conditions the GaSb surface presents a (1x3) reconstruction. Anneal ing under Sb, flux induces the formation of (1x5) or (2x5) reconstruct ions. Annealing under As-4 flux leads, for T<400 degrees C, to As-Sb e xchanges in the surface layer and, for T>450 degrees C, to the desorpt ion of Sb atoms accompanied by the formation of GaAsSb microphases.