X-ray induced variation of the chemistry of GaAs/AlAs oxide nanostructures

The variation of the surface chemical composition of nanostructures fabricated by local anodic oxidation (LAO) on epitaxial GaAs/AlAs/GaAs layered structures is investigated by means of laterally-resolved photoemission spectroscopy. Our analysis evidences the unexpected presence of Al compounds located in the topmost layers of the LAO oxide structures. We studied the evolution of the surface chemical composition of such nanostructures as a function of X-ray exposure time (photon energy hν = 130 eV) and we found a reduction in the amount of the surface Ga oxide compounds with respect to the Al compounds.