Surfaces of (001) type were treated ultrasonically with de-ionised water, after etching with NH4OH-H2O2-H2O mixtures, and were investigated by means of reflection high-energy diffraction and X-ray photoelectron spectroscopy. The former technique revealed the presence of a spotty 1 x 1 pattern on the zeroth Laue circle (at room temperature), a 2 x 4 streaky pattern at 310C, and a spotty 3 x 6 pattern after annealing at 370C. The results indicated that it might be possible to control the surface stoichiometry by modifying the etchant solutions.

Y.Hirota, Y.Homma, K.Sugli: Applied Physics Letters, 1991, 59[26], 3410-2