Low-energy electron diffraction, Auger electron spectroscopy and photo-emission yield spectroscopy measurements were performed on GaAs samples cleaved in ultra-high vacuum and subject to in situ isochronous annealing up to 850C. The properties of the cleaved (110) surface remained unchanged up to about 350C. Around this temperature, a dissociation occurred inducing a local reconstruction of the surface; at the same time, new states appear which could be attributed to Ga vacancies. Then, around 580C, the well known dissociation of GaAs sets in with formation of As2, and the Ga-Ga bonds which then form, determine the electronic properties of the sample. Evaporation of arsenic would become dominant around 650C. Beyond about 780C, the excess Ga coalesces into Ga-metal droplets and the GaAs substrate underwent faceting.

Effects of Vacuum Annealing on the Electronic Properties of Cleaved GaAs. F.Proix, A.Akremi, Z.T.Zhong: Journal of Physics C, 1983, 16[28], 5449-63