SOLVENT-AFFECTED CHEMISTRY AT GaAs/SULFIDE SOLUTION INTERFACE

摘要

The chemistry of GaAs(100) oxide-free surfaces treated with solutions of (NH_4)_2S in different solvents (water, alcohols) was studied by photoemission in order to clarify the role, which solvent plays in the course of adsorbate interaction with the surface atoms at the semiconductor/solution interface. Adsorption of sulfur from solution results in appearance of As-S bonds with solvent-dependent ionicity (more ionic bonds are formed in low dielectric constant alcohols). Valence band spectra of GaAs(100) surfaces after annealing contain the Ga-S related valence band state. The binding energy of this state increases with the decrease of the solvent dielectric constant. The obtained variation of the surface chemistry with change of the solvent is related to the variation of HS~- ion reactivity due to the different influence of the solvate shell.