Visualizing anisotropy in the surface oxidation of germanium by wet etching of patterned nanowedges: proof of concept.

We study the anisotropy in surface oxidation for Ge(100) and (110) in HCl/H2O2 solution complemented by synchrotron X-ray photoemission spectroscopy (SXPS) measurements integrated with an in situ etching chamber. Visual anisotropic demonstration is confirmed by lithographic Ge nanowedges.

Interaction of liquid water with the p-GaInP(100) surface covered with submonolayer oxide.

High-resolution surface-sensitive synchrotron radiation photoelectron spectroscopy was used to study the interaction of water with the p-GaInP2(100) surface covered with submonolayer residual native oxide in order to get insight into water dissociation at the solar water-splitting photocathodes in real liquid environment. In the surface-sensitive valence band spectra features related to Ga-OH, In-OH, and H-In-OH bonds appear after emersion of the p-GaInP2(100) surface from liquid water at room temperature. Indium core levels remain intact after emersion, while the gallium core levels indicate transformation of gallium oxides to hydroxides, as well as the accumulation of metallic gallium.

Synchrotron photoemission analysis of semiconductor/electrolyte interfaces by the frozen-electrolyte approach: interaction of HCl in 2-propanol with GaAs(100).

Perspectives of a new approach for the synchrotron photoemission spectroscopic analysis of chemical processes at solid/liquid interfaces under UHV conditions have been explored. A thin layer of HCl-2-propanol solution was frozen-in on the semiconductor GaAs(100) wafer surface by cooling the substrate to liquid nitrogen temperature after etching off the native oxide layer under N2 atmosphere. Chemical reactions induced in situ by exposure to synchrotron radiation (SR) and by stepwise heating have been monitored.