Effect of Crystal Structure on the Behavior of Diamond Electrodes

Abstract

Effects of crystal structure on the electrochemistry of boron-doped high temperature-high pressure (HTHP) diamond single crystals grown from a Ni-Fe-C melt are studied. On the {111}, {100}, and {311} faces, the linear and nonlinear electrochemical impedance measurements were performed and the rate of electron transfer for normalFefalse(CN)63­/4­ was evaluated. Like polycrystalline chemical vapor deposited films, the HTHP electrodes’ equivalent circuit includes a constant phase element. The uncompensated acceptor concentration in the semiconductor diamond was determined from Mott-Schottky plots and amplitude-demodulation measurements and was found to vary in the range of 1018 to 1021 cm−3. The difference in the electrochemical behavior of individual crystal faces is primarily attributed to different boron concentrations in the growth sectors associated with the faces. © 2002 The Electrochemical Society. All rights reserved.

Electroanalysis at Diamond‐Like and Doped‐Diamond Electrodes

“…Depending on the pre-treatment (and the quality) of borondoped diamond electrodes either reversible or quasireversible electron transfer is observed (see Figure 5). It is interesting to note the shape of voltamametric signals for quasi-reversible systems is not consistent with the −textbook× case [82] and that the tell-tale change in peak current (see Figure 5) is probably mainly attributable to different rates of electron transfer at different crystal faces [83] (compare SEM images in Figure 4). …”

Using Scanning Electrochemical Microscopy to Determine the Doping Level and the Flatband Potential of Boron‐Doped Diamond Electrodes

“…The standard potential of IrCl 6 2À/3À was determined to be E 0 F, redox = 0.70 V Ag/AgCl . Considering the range of the flatband potential values found in the literature, (E FB % 0.4-1.6 V Ag/AgCl ), [8,[13][14][15][16][17][18][19] it is expected that, for this redox couple, electron exchange will occur essentially through the valence band.…”

“…The majority chargecarrier concentration of the boron-doped diamond samples was usually obtained from electrochemical impedance spectroscopy, by a Mott-Schottky analysis of the differential capacitance of the space charge region. [8,[13][14][15][16][17][18][19] This technique also provides the flatband potential of the diamond/electrolyte interface. However, the frequency dependent N A and the flatband potential values found in the literature are rather dispersed, probably owing to the poor linearity of the reported Mott-Schottky plots.…”

“…However, the frequency dependent N A and the flatband potential values found in the literature are rather dispersed, probably owing to the poor linearity of the reported Mott-Schottky plots. [8,[13][14][15][16][17][18][19] Therefore, another way of assessing E F FB as well as N A would be beneficial.…”

The Use of Conducting Diamond in Electrochemistry

“…In the literature, there is only one report of a different substrate used to grow sc diamond by CVD; sc iridium [30]. HPHT has also been used to grow sc BDD specifically for electrochemical studies [31]. Understanding the CVD growth mechanism and optimizing growth conditions [32] to minimize defect formation and impurity incorporation is essential for obtaining high-quality, highly doped sc BDD materials [33] suitable for electrochemistry.…”