Quantitative Analysis of Semiconductor Electrode Voltammetry: A Theoretical and Operational Framework for Semiconductor Ultramicroelectrodes

Abstract

A thorough framework for how to interpret and predict the steady-state voltammetric responses of semiconductor ultramicroelectrodes (SUMEs) has been compiled. Through consideration of the Marcus–Gerischer treatment for heterogeneous charge transfer and the interplay between the fractions of the applied potential that drop across the space-charge region, the solution, and their interface in depletion and accumulation conditions, the complex potential dependences of the majority carrier densities, n s, and the rate constant for electron transfer from the conduction band edge, k et, are identified. Incorporation of these terms in the conventional fitting procedures of steady-state voltammetry at inlaid disk electrodes affords determination of the full J–E responses of n-type SUMEs in a variety of experimental permutations. Working curves are presented to illustrate how the specific values of the conduction band edge potential, the reorganization energy for charge transfer, the standard potential of the redox species, and the doping density control the form of the voltammetric responses of a pristine semiconductor/electrolyte interface. Further working curves are provided to highlight the expected influence of surface states on the steady-state voltammetry of SUMEs. An example of how to analyze experimental data without the use of “non-ideality” factors is shown, illustrating that it is possible to extract validated estimates of heterogeneous charge-transfer constants and the defect character of the semiconductor/electrolyte interface. In total, this work provides a clear guide for utilizing simple, raw voltammetric data from SUMEs to study semiconductor/electrolyte contacts of interest.

Light-Addressable Electrochemical Sensing with Electrodeposited n-Silicon/Gold Nanoparticle Schottky Junctions

“…With metallic electrodes, the HET rate is not typically affected by charge transport in the metal. However, with semiconductors, charge transfer, recombination, diode quality, and interfacial properties can all impact the overall rate . On the basis of the shape of the CVs in Figure b and the close agreement with the Randles–Sevcik equation (eq ), we hypothesized that the HET rate constant, k 0 , could be measured using the Nicolson method, where the peak-to-peak separation in a CV is related to the dimensionless parameter, ψ. , This assumption would only account for HET across the metal/solution interface and imply that charge transfer in the semiconductor and across the semiconductor/metal interface is considerably faster than the electron transfer rate.…”

“…17 In straightforward cases, voltammetry at a semiconductor/electrolyte interface is influenced not only by mass transport of redox species and electron transfer across the interface but also by potential corrosion of the semiconductor in an aqueous electrolyte as well as carrier dynamics within the semiconductor. 18 Each of these factors must be carefully controlled in order to have sensors that give reliable data and are reproducible.…”

“…Designing LAES for practical applications is considerably more challenging than designing electrochemical sensors based on metallic or carbon electrodes because the semiconductor/electrolyte interface is more difficult to control than a metallic electrode/electrolyte interface . In straightforward cases, voltammetry at a semiconductor/electrolyte interface is influenced not only by mass transport of redox species and electron transfer across the interface but also by potential corrosion of the semiconductor in an aqueous electrolyte as well as carrier dynamics within the semiconductor . Each of these factors must be carefully controlled in order to have sensors that give reliable data and are reproducible.…”

Description of Solid-to-Solid Redox Processes Based on the Voltammetry of Immobilized Particles Methodology: A Logistic Approximation

“…3−5 The electrochemistry of surface-confined species, however, is not limited to adsorbates, and theoretical studies include nanoparticles 6 and droplets 7 anchored to�or impacting onto�electrodes, porous electrodes, 8 and microparticulate deposits of insulating or semiconducting solids. 9 Recently, interactions between immobilized redox centers, 10,11 semiconductor electrode voltammetry 12 giving rise to phase transitions, 13 and charge transfer in solid-state redox processes 14 have been treated.…”

Microelectrode arrays with active-area geometries defined by spatial light modulation

“…Transient microelectrode arrays created using a spatial light modulator and unstructured macroscopic photoconductors, or semiconductors, can be a tool for chemical analysis with [Type here] performances comparable to those of conventional microelectrodes [29], but with the advantage of lifting almost entirely geometrical restrictions on the active area. [Type here]…”