THERMAL EFFECTS ON THE GROWTH OF SIO2 ON GAAS(100) BY REDUCTION OF NATIVE OXIDES

The reactivity of Si with oxidized GaAs surfaces has been recently proposed as a new pathway to form SiO2/GaAs interfaces. In this work, we study the maximum amount of native oxides which can react with evaporated Si atoms, leading to a complete reduction of the GaAs-oxides. Photoemission techniques, using synchrotron radiation and conventional x-ray sources, were used to monitor in situ the interface formation. The completion of the native oxides reduction is limited to layers around 5 angstrom thick at room temperature, though substrate heating at 550 K during Si deposition allows this limitation to be overcome. This temperature seems to be high enough to activate the diffusion of the Si monomers to the inner interface so that the reduction process can continue. The reduction process stops when Si monomers cannot diffuse through the Si-oxide la er and Si-Si bonds are formed on top of the oxide layer.