GaAs(111)AandBsurfaces in hydrazine sulfide solutions: Extreme polarity dependence of surface adsorption processes

Abstract

Chemical bonds formed by hydrazine-sulfide treatment of GaAs(111) were studied by synchrotron photoemission spectroscopy. At the B surface, the top arsenic atoms are replaced by nitrogen atoms, while GaAs(111)A is covered by sulfur, also bonded to underlying gallium, despite the sulfide molar concentration being 10 3 times smaller than that of the hydrazine. This extreme dependence on surface polarity is explained by competitive adsorption processes of HS -and OH -anions and of hydrazine molecules, on Ga-adsorption sites, which have distinct configurations on the A and B surfaces.

Carrier Recombination Processes in GaAs Wafers Passivated by Wet Nitridation

“…Surface nitridation by hydrazine sulfide solution can form a GaN monolayer at the GaAs surface. This monolayer can protect the crystal surface against oxidation over a period of months and significantly improve the GaAs optical and electrical properties. ,− Overall, surface nitridation is a stable and effective method for passivation of the GaAs surface. However, a comprehensive description of processes influenced by nitride passivation, in particular carrier recombination processes, is not yet available.…”

Surface Termination Control in Chemically Deposited PbS Films: Nucleation and Growth on GaAs(111)A and GaAs(111)B

“…Surface characteristics are one of the key parameters influencing the performance and degradation of electronic and optoelectronic devices. There are numerous examples showing that distinct physical and chemical behavior can be attributed to distinct termination of semiconductor surfaces. − Furthermore, occurrence of epitaxial growth frequently depends on substrate polarity . For instance, the importance of the physicochemical interactions between the two different InP faces and the chemical species present in the deposition solution were highlighted by Lincot et al, who established that CdS growth is very sensitive to the polarity of the substrate, changing from polycrystalline films obtained on the In-terminated InP(111) face to epitaxial growth on the P-terminated InP(1̅1̅1̅) face .…”

Nitride Surface Passivation of GaAs Nanowires: Impact on Surface State Density

“…19,20 However, such treatment is known to produce surface microetching, which might remove a few monolayers of the GaAs material. 20,24 To avoid microetching and to prevent possible damage to the NW surface morphology, we used a low alkaline (pH ∼ 8.5) hydrazinesulfide solution in which concentration of the OH− anions is intentionally decreased by 4 orders of magnitude and microetching becomes nearly impossible. 23 Preparation of the solution included the two following stages.…”

“…Thus, surface passivation can be provided only by a continuous nitride film with monolayer thickness. It has been demonstrated that such notably thin GaN surface films can be prepared on GaAs (100) and (111) B surfaces as a result of a rather simple wet chemical treatment in hydrazine-sulfide solution at room temperature. , The chemistry of the wet nitridation is described in detail in ref . The surface nitride monolayer forms as a result of successive chemical reactions, which begin with the removal of surface oxide under ambient alkaline conditions.…”

“…For surface nitridation of GaAs crystals, wet chemical treatment in highly alkaline (pH ∼ 12) hydrazine-sulfide is conventionally used. , However, such treatment is known to produce surface microetching, which might remove a few monolayers of the GaAs material. , To avoid microetching and to prevent possible damage to the NW surface morphology, we used a low alkaline (pH ∼ 8.5) hydrazine-sulfide solution in which concentration of the OH– anions is intentionally decreased by 4 orders of magnitude and microetching becomes nearly impossible . Preparation of the solution included the two following stages.…”