Surface nitridation by hydrazine-sulfide solution, which is known to produce surface passivation of GaAs crystals, was applied to GaAs nanowires (NWs). We studied the effect of nitridation on conductivity and microphotoluminescence (μ-PL) of individual GaAs NWs using conductive atomic force microscopy (CAFM) and confocal luminescent microscopy (CLM), respectively. Nitridation is found to produce an essential increase in the NW conductivity and the μ-PL intensity as well evidence of surface passivation. Estimations show that the nitride passivation reduces the surface state density by a factor of 6, which is of the same order as that found for GaAs/AlGaAs nanowires. The effects of the nitride passivation are also stable under atmospheric ambient conditions for six months.

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We demonstrate a new approach to study semiconductor surface passivation. This approach, which we have applied to the case of GaAs(100) passivation by sodium sulfide water solutions, consists of using both reflectance anisotropy spectroscopy during passivation and ultraviolet photoemission spectroscopy after removing the sample from the solution. We find that (i) complete chemical passivation requires a treatment duration significantly longer than what was used in previous works; in our case, the oxygen contamination is strongly reduced; (ii) photochemical processes play an important role for improving the surface electronic properties. As a result, photoemission spectroscopy, which uses powerful light excitation, may strongly alter the chemical bonds. From experimental evidence and using a chemical model based on first principles estimates, we propose a detailed description both of the surface chemical reactions that occur during passivation and of the chemical bonds that are formed at the semiconductor surface and in the passivating overlayer.

GaSb(100) surface electronic passivation with aqueous Na2S solution is driven by the redox reaction of gallium sulfide and elemental antimony formation.

Photoluminescence, Raman scattering, as well as x-ray photoelectron spectroscopy are used to study the electronic structure of n-InP(100) surfaces modified with different sulfide solutions. Because of such a modification, the...