Photoelectrochemical Processes at n-GaAs(100)/Aqueous HCl Electrolyte Interface: A Synchrotron Photoemission Spectroscopy Study of Emersed Electrodes

Abstract

High-resolution synchrotron photoemission spectroscopy has been applied to detail the electrochemical and photoelectrochemical corrosion reactions at the liquid junction n‑GaAs(100)/1 M aqueous HCl solution. Under anodic polarization of 1.8 eV, the main process initiated by the presence of holes in the Ga–As bonding states of the valence band is the formation of soluble gallium chloride complexes and insoluble elemental arsenic on the surface. In addition, arsenic hydroxide forms, which reacts further to soluble HAsO2. In toto, the As/Ga atomic ratio increases, which is accompanied by an increase of the work function. The anodic decomposition reaction is enhanced by illumination as more holes reach the n-semiconductor/electrolyte junction. Under cathodic polarization of 1.5 eV, only minor changes are observed in Ga and As core-level spectra, giving no indication of corrosion, but specific adsorption of hydrated HCl molecules and/or Cl– ions considerably modifies valence band spectra.

Nanoscale etching of III-V semiconductors in acidic hydrogen peroxide solution: GaAs and InP, a striking contrast in surface chemistry

“…According to various authors GaAs (100), pretreated in HCl solution, should be essentially oxide-free. [40][41][42][43][44] Oxide growth, observed with our sample, must have occurred during the water rinsing step and/or transfer of the sample to the spectrometer; the conditions were not completely oxygen-free. GaAs (100), without water rinse.…”

A Hierarchical 3D TiO2/Ni Nanostructure as an Efficient Hole‐Extraction and Protection Layer for GaAs Photoanodes

“…The hierarchical 3D/TiO 2 /Ni nanostructure not only serves as a charge transfer channel to reduce the charge flux, but also avoids charge accumulation at the photoelectrode surface, and suppresses recombination of photocarriers at the semiconductor/electrolyte interface. Despite the fact that GaAs is more susceptible to photocorrosion under anodic potential than under cathodic potentials, [17] we introduce the hierarchical 3D/TiO 2 /Ni bi‐functional nanostructure, as both a charge transfer and a surface protection layer, to enhance the charge‐separation efficiency and at the same time to reduce photocorrosion of the III‐V photoanode.…”

Extended glass‐forming region in the AgCl‐Ag2S‐As2S3 ternary system

“…However, it fails to fit the As 3d doublet associated with the As–Cl bond. It is known that the S and Cl elements are adjacent to each other in the periodic table, and they have similar atomic radii and electronegativities with a small BE difference (~0.1 eV), thus it is difficult to identify between the As–S and As–Cl bonds. This is also the reason why the As 3d doublet (I As ) of all AgCl‐containing samples shows larger FWHM values than the AgCl‐free samples (~1.15 eV for G0‐0.66 glass).…”