“…The energy positions at the surface for several semiconductors in contact with aqueous solutions are given in Figure . In many cases the flat-band potential, U fb , and consequently the position of the energy bands, varies with the pH of the solution because of protonation and deprotonation of surface hydroxyl groups, as especially found with oxide semiconductors, germanium, and some III−V compounds (for detailed information see for example review articles ,,,− ). 4 (a) Photocurrent−potential curve for n-type WSe 2 semiconductor electrode. (b) Mott−Schottky plots for n-type WSe 2 electrode in 2 M HCl in the dark and under various intensities of illumination. 5 Equilibration of Fermi levels across semiconductor−liquid interface showing band bending in the semiconductor space charge (depletion) layer when the band edges are pinned. 6 Position of energy bands of various semiconductors in the dark (d) and in light (l) with respect to the electrochemical scale.…”
The science describing semiconductor−liquid
interfaces is highly interdisciplinary, broad in scope,
interesting,
and of importance to various emerging technologies. We present a
review of the basic physicochemical
principles of semiconductor−liquid interfaces, including their
historical development, and describe the major
technological applications that are based on these scientific
principles.
“…The energy positions at the surface for several semiconductors in contact with aqueous solutions are given in Figure . In many cases the flat-band potential, U fb , and consequently the position of the energy bands, varies with the pH of the solution because of protonation and deprotonation of surface hydroxyl groups, as especially found with oxide semiconductors, germanium, and some III−V compounds (for detailed information see for example review articles ,,,− ). 4 (a) Photocurrent−potential curve for n-type WSe 2 semiconductor electrode. (b) Mott−Schottky plots for n-type WSe 2 electrode in 2 M HCl in the dark and under various intensities of illumination. 5 Equilibration of Fermi levels across semiconductor−liquid interface showing band bending in the semiconductor space charge (depletion) layer when the band edges are pinned. 6 Position of energy bands of various semiconductors in the dark (d) and in light (l) with respect to the electrochemical scale.…”
The science describing semiconductor−liquid
interfaces is highly interdisciplinary, broad in scope,
interesting,
and of importance to various emerging technologies. We present a
review of the basic physicochemical
principles of semiconductor−liquid interfaces, including their
historical development, and describe the major
technological applications that are based on these scientific
principles.
“…Due to their nanocrystalline structure, the latter have a significant grain boundary area, which can profoundly influence the electrochemical behavior [2]. The thickness of the thin films (10 ± 100 nm) is comparable to the expected extension of the space charge region (10 ± 10 3 nm [3,8]) showing, thus, a space charge capacitance higher than the expected values for a semi-infinite medium. The structure of MS-ZnO/electrolyte was shown to be non-blocking at both acid and basic pH values due to the higher reactivity of the polycrystalline morphology of the oxide [2,6,7].…”
“…The physical and chemical phenomena that occur when an electric field is applied at the electrode-liquid interface have been extensively discussed in the literature 43,44 .…”
Retrieving electrical impedance maps at the nanoscale rapidly via nondestructive inspection with a high signal-to-noise ratio is an unmet need, likely to impact various applications from biomedicine to energy conversion. In this study, we develop a multimodal functional imaging instrument that is characterized by the dual capability of impedance mapping and phase quantitation, high spatial resolution, and low temporal noise. To achieve this, we advance a quantitative phase imaging system, referred to as epi-magnified image spatial spectrum microscopy combined with electrical actuation, to provide complementary maps of the optical path and electrical impedance. We demonstrate our system with high-resolution maps of optical path differences and electrical impedance variations that can distinguish nanosized, semi-transparent, structured coatings involving two materials with relatively similar electrical properties. We map heterogeneous interfaces corresponding to an indium tin oxide layer exposed by holes with diameters as small as ~550 nm in a titanium (dioxide) over-layer deposited on a glass support. We show that electrical modulation during the phase imaging of a macro-electrode is decisive for retrieving electrical impedance distributions with submicron spatial resolution and beyond the limitations of electrode-based technologies (surface or scanning technologies). The findings, which are substantiated by a theoretical model that fits the experimental data very well enable achieving electro-optical maps with high spatial and temporal resolutions. The virtues and limitations of the novel optoelectrochemical method that provides grounds for a wider range of electrically modulated optical methods for measuring the electric field locally are critically discussed.
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