X-ray photoelectron spectroscopy of ammonium sulfide treated GaAs (100) surfaces

Abstract

The effect of an ammonium sulfide treatment on the GaAs (100) surface has been investigated by x-ray photoelectron spectroscopy. The treatment produces a slight Ga enrichment on the surface and leaves roughly 0.6 of a monolayer of sulfide which inhibits initial oxidation of the surface. The sulfide is not lost as the surface becomes oxidized but appears to remain near the GaAs/oxide interface. Furthermore, in the oxidized layer, As oxide is preferentially drawn to the surface relative to Ga oxide.

Stability of sulfur-treated InP surface studied by photoluminescence and x-ray photoelectron spectroscopy

“…4 The monosulfide must contain only In-S bonds because peaks by P-S bonds were not detected ͑see Fig.2͒. Since the thickness of In-S overlayers in S-treated InP surfaces does not exceed two monolayers, 26,27 it is considered that the surface of lightly S-treated InP used in this work is also covered with one or two monolayers of In-S bonds. This argument is confirmed by the observation that the S 2 p core level XPS spectrum in the range of 162-166 eV corresponding to elemental sulfur 4 is detected from the InP surface covered with a thick S overlayer ͓see Fig.…”

“…The thickness of this S overlayer is similar to that obtained by simply dipping InP in ͑NH 4 ) 2 S x solution. 26,27 The samples were subsequently rinsed by DI water for about 10 s. Even if the growth of a thick S overlayer with high current density was efficient to protect the surface, we intentionally used a small current density for the following two reasons: ͑i͒ The surface degradation phenomenon can be observed more easily with a thin S overlayer.…”

Field - dipole interactions in L-cysteine-thiolate self assembled at p- and n-GaAs(100) electrodes

“…3c) were fitted with 3 peaks assigned to As-S species (BE = 1324.9 AE 0.2 eV), As-O species (BE = 1326.2 AE 0.2 eV) and substrate As atoms (BE = 1323.2 AE 0.2 eV), whereas the Ga-2p 3/2 spectrum (Fig. 3d) has only contributions from the substrate Ga atoms (BE = 1117.6 AE 0.2 eV) and Ga-O species (BE = 1118.9 AE 0.2 eV) according to the literature data [21][22][23][24]. Although the Ga-bound thiolate species cannot be discerned with our instrumentation as mentioned before [15], the low content of Gaoxide species is an indirect proof that Ga atoms compete as well with As atoms in this respect as in the case of other thiolates formed on GaAs substrates [15,25,26].…”

X-ray Photoelectron Spectroscopic Studies of Sulphur-passivated GaAsSurfaces

“…9H,O aqueous solution can provide very good electronic passivation, its chemical passivation is rather poor. 7 The main problem is its instability. The ordinary sulphur treatment results in only one monolayer of sulphur atoms bonded to GaAs surface, which are very easily replaced by oxygen after a long time of exposure to air, especially under illumination.…”