Angle resolved XPS spectra (dots) and fits (lines) for the as-deposited sample.
Take-off angle dependence of the peak areas for the as-deposited sample. The solid lines correspond to theoretical behavior generated according to the physical model inserted.
XPS spectra of (a) As 3d, Ti 3p, Hf 5p, (b) Hf 4d, As 3s, (c) Ga 3p, and (d) In 3d 5/2 for the various samples. The Hf 4d signal remains relatively constant after the thermal treatments. However, a slight increment in the Ga-O signal and an oxidation in the In 3d 5/2 region is observed when the anneal temperature was above 500 °C.
The experimental dependence of the area of In and Ga peaks associated with O bonds (symbols) are compared with the theoretical behavior (lines) under different scenarios of their location. This comparison allows for a robust determination of their depth distribution. The dependence of the signal from oxidized indium for the (a) 500 °C/120 s sample and (b) 700 °C/10 s sample is clearly compatible with a location in the metallic layer (curves “2”) and incompatible with a location at the interface (curves “1”), indicating the presence of indium in the Ti layer. (c) After 700 °C annealing, the location of the oxidized gallium signal is compatible with the metallic layer, indicating diffusion of Ga atoms from the substrate to this layer (curve “2”).
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