Auger electron spectroscopy sputter depth profiles on AlxGa1-xAs protected by As and GaAs ultrathin layers

The Auger electron spectroscopy sputter depth profiling technique has been used to evaluate the protective efficiency of ultrathin overlayers of As (∼25 Å) and GaAs (25 Å) against air exposure damaging effect of AlxGa1-xAs (x=0.3) epitaxial layers. It is shown that the As adsorbed overlayer is only partially effective to protect AlxGa1-xAs surface for a short air exposure. The surface of this reactive material can be more efficiently protected by GaAs, even for a very thin overlayer (25 Å). Results dealing with the effects of air and H2 annealings on the AlxGa1-xAs surface are also reported. They confirm the Ga segregation at the AlxGa1-xAs surface recently reported [Stall et al., J. Vac. Sci. Technol. B 3, 524 (1985) and Massies et al., ibid. 3, 613 (1985)].