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The impact of non-ideal surfaces on the solid-water interaction: a time-resolved adsorption study

by Matthias M. May, Helena Stange, Jonas Weinrich, Thomas Hannappel, Oliver Supplie

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Submission summary

Authors (as registered SciPost users): Matthias May · Oliver Supplie
Submission information
Preprint Link:  (pdf)
Date accepted: 2019-05-06
Date submitted: 2019-04-30 02:00
Submitted by: May, Matthias
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • Atomic, Molecular and Optical Physics - Experiment
  • Condensed Matter Physics - Experiment
Approach: Experimental


The initial interaction of water with semiconductors determines the electronic structure of the solid-liquid interface. The exact nature of this interaction is, however, often unknown. Here, we study gallium phosphide-based surfaces exposed to H2O by means of in situ reflection anisotropy spectroscopy. We show that the introduction of typical imperfections in the form of surface steps or trace contaminants not only changes the dynamics of the interaction, but also its qualitative nature. This emphasises the challenges for the comparability of experiments with (idealised) electronic structure models for electrochemistry.

Author comments upon resubmission

We thank the Referee for the suggestions, which we believe to have addressed in our revision.

Regarding the "V-rich" terminology, we have made this clearer in the introduction part by adding "The group-V-rich (in the following termed “V-rich”) surface".

With respect to the terraces, we now have included an AFM image (together with a new paragraph on page 10) showing them on the 0.1 deg surface. Unfortunately, for the 2 deg surfaces, the spacing of 8 nm is too low to resolve them. STM could in principle be an option here, but unfortunately, GaP surfaces are rather notorious with respect to STM imaging.

List of changes

- We added "The group-V-rich (in the following termed “V-rich”) surface" on page 4.
- We added an AFM image (Figure 8), together with the paragraph "From a quantitative perspective, the step density follows from terrace width and step
height. In the case of single-domain surfaces, the surface exhibits double-steps (or whole multiples thereof) with the height of half of a lattice constant (a 0 = 5.45 Å). If anti-phase domains exist, the step height is only a quarter of a lattice constant. For single-domain surfaces, this results in ca. 160 nm wide terraces for 0.1 deg substrates, and 8 nm for 2 deg. In Fig. 8, we show an atomic force microscopy (AFM) of a sample with a 300 nm thick GaPN layer on top of an Si(100) substrate with 0.1 deg misorientation. The observed terraces are 120-200 nm wide along the [011] direction, indicating that the substrate terraces do indeed
propagate to the surface of the heteroepitaxial layer. The homoepitaxial GaP(100) samples with nominally no misorientation did, as well as GaPN layers on GaP, not show these terraces. For 2 deg samples, it was not possible to resolve terraces, anymore, owed to their narrow width of only 8 nm."
- We extended the funding information and the authors contributions section.

Published as SciPost Phys. 6, 058 (2019)

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