ULTRAVIOLET-OZONE OXIDATION OF GAAS(100) AND INP(100)

This article reports on a study of the ultraviolet (UV)-ozone oxidatio n of GaAs(100) and InP(100) using high-resolution x-ray photoelectron spectroscopy (XPS) complemented by transmission electron microscopy (T EM). For GaAs(100), various oxides As2O3, As2O5, and Ga2O3 are observe d. The As2O3 core level intensity follows a logarithmic growth, while AS2O5 and Ga2O3 exhibit a linear growth as a function of UV-ozone expo sure time. Angle-resolved XPS and TEM measurements confirm that the ox ide has a layered structure represented sehematically as (AS2O5, Ga2O3 )/(AS2O3, Ga2O3)/GaAs(100). Two different oxidation processes likely o ccur; the first is bulk oxidation at the GaAs(100)/oxide interface, an d the second process occurring at the higher oxide/lower oxide interfa ce is conversion of the lower As oxide to the higher As oxidation stat e. On InP (100), oxides corresponding to In2O3 and PO(x) are observed, and the respective photoelectron intensities follow a logarithmic gro wth as a function of UV-ozone exposure time. Angle-resolved XPS measur ements show that the In2O3 and PO(x) are homogeneously mixed. The tota l oxide thickness, calculated from the photoelectron intensity ratio, follows a logarithmic growth as a function of exposure time on both Ga As(100) and InP(100).