RHEED and XPS Study of Oxide Desorption from InSb(100) Substrates

Oxide desorption from InSb(l00) substrates is studied using RHEED, XPS, AES and SEM. We observe a multi-stage desorption process for surfaces prepared using either of two common chemical etchants. A composite oxide containing In₂O₃ and Sb₂O₅ is evident in as-loaded substrates. During the first stage, most of the Sb oxide is reduced, leaving behind a thin oxide layer consisting predominantly of In₂O₃. As T_sub is raised further in the presence of an Sb flux, desorption of In₂O₃ is evident. SEM images of substrates removed from the MBE chamber at various times during the desorption process indicate that In droplets condense on the surface before a smooth morphology ensues. We suggest that In reduced from In₂O₃ form droplets which then react with the supplied Sb flux to form InSb. Annealing at this temperature eventually produces a smooth, stoichiometric surface which results in a welldefined, Sb-stabilized pseudo-(lX3) RHEED pattern. InSb films grown on such substrates exhibit good structural and electrical properties.