Platinum- (Pt-) enhanced oxidation of GaAs has been investigated using high-resolution x-ray photoelectron spectroscopy (XPS). A thin oxide layer of thickness in the range 0.5-1.6 nm is formed on the GaAs surface and then a Pt layer is deposited on it. Heat treatments at 200 °C in oxygen increase the oxide thickness to 2.4-4.7 nm. Measurements of the take-off angle dependence of the XPS spectra show that the oxide layer has nonuniform layerlike structure, consisting of gallium oxide, arsenic oxide, and elemental arsenic; each oxide component is present between the Pt overlayer and the Si substrate, but is not on the Pt layer. Arsenic oxide is present just below the Pt layer, while gallium oxide and elemental arsenic are present below it. Oxygen atoms produced at the Pt surface are suggested to be the diffusing species through the Pt layer. On the other hand, the moving species in the oxide layer are arsenic and gallium atoms as well as oxygen atoms. The oxide thickness depends on the nature of the oxide layer formed before the Pt deposition, and is mainly attributed to the different composition of the oxide layers. Gallium oxide is suggested to suppress the diffusion of the reacting species.
|Number of pages||7|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 1997 Jan 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics