GaAs(100) substrate cleaning by thermal annealing in hydrogen

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Abstract
The removal of residual surfacecontaminants from chemically polished GaAs wafers has been examined with x‐ray photoelectron spectroscopy. Al Kα‐excited As 2p3/2 and Ga 2p3/2 core level spectra with a shallow probing depth show complete desorption of As3 +surface oxide after annealing in a stream of pure hydrogen at atmospheric pressure and 400 °C, whereas a temperature of 600 °C is required for entire removal of the Ga3 +surface oxide. Carbonaceous surface impurities are also shown to be efficiently reduced by this hydrogen processing. The recorded core level peak intensities indicate formation of a fully stoichiometric substrate surface, with no depletion of arsenic. The chemical structure of the hydrogen processed surface compares favorably with that found for substrates annealed in an ultrahigh vacuum environment. In contrast, annealing at 600 °C in 1 atm of high‐purity inert gas (argon) is shown to promote formation of a thick Ga–oxide on the substrate surface, thus emphasizing the reactive nature of the ambient in this hydrogen processing.

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