Electroreflection Measurements on Semiconductor/Electrolyte Interfaces to Determine the Voltage Distribution

Abstract

The electroreflectance signal from a semiconductor electrode surface is sensitive to the magnitude of the space charge. It is used to determine the voltage distribution between the space‐charge layer and the Helmholtz double layer at an electrode/electrolyte interface. In this paper, the first of two, we describe the experimental arrangements and measurements of the electroreflectance spectra for normaln‐MoSe2 and normaln‐WSe2 under anodic and cathodic bias. Important features in the spectra are found to be in agreement with existing theories. Flatband values inferred from the electroreflectance spectra are in agreement with those from Mott‐Schottky plots. The effects of Fermi level pinning on the electroreflectance spectra are demonstrated with normaln‐normalGaAs .

A Study of Charge Transfer at an Illuminated p ‐ InP Electrode in Aqueous Solution

“…Most authors attribute band-edge movement to either carrier inversion or Fermi-level pinning (12,54). Carrier inversion occurs in semiconductors when the band bending is sufficiently large to bring the Fermi level close to the minority carrier band at the surface.…”

“…One method by which this can be achieved is to monitor the potential drop across the Helmholtz double layer. A recent paper of Scholz and Gerischer (54) reported a new technique for determining the voltage distribution between the space charge layer and the Helmholtz double layer at an electrode/electrolyte interface. This new technique may help to clarify the surface energetics at semiconductor/solution interfaces.…”

Electrolyte electroreflectance study of TiO2 films modified with metal nanoparticles

“…When the modulated electric field is sufficiently low, the line shape of the EER spectrum of a nondegenerate semiconductor is determined by the modulation-induced effect of populationdepopulation of the electronic surface states (in the sub-band-gap absorption range) or is closely related to the third derivative of the dielectric function (in the bandgap absorption range). 1 This spectroscopic technique was used to determine the potential distribution inside the nanocrystalline films 2 and between the space charge layer and Helmholtz or surface oxide layer, [3][4][5] to study the evolution of space charge region in the degenerated semiconductors contacting with the electrolyte solution, 6 to measure flat-band potentials, 4,7,8 and to obtain information on the degree of inhomogeneity of an electrode surface. 8,9 The EER measurements have also proven to be particularly useful as a means for the identification of the electroactive surface states.…”

Carbon Film Oxidation‐Undercut Kinetics

“…[20] d From [7] and [8] we conclude that the gas velocity in region 1 is zero. Carbon transport in region 1 is by diffusion only d Jcl =-Doc dxx [COs] = -Doc(Pf/RTd) [9] In the absence of a gas velocity the concentration profiles of COs and Os in region 1 are linear interpolations of the boundary conditions [3]- [6].…”