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Effect of electrolyte concentration on anodic nanoporous layer growth for n-InP in aqueous KOH
Lynch, Robert P.; O'Dwyer, Colm; Buckley, D. Noel; Sutton, David; Newcomb, Simon B.
The surface morphology and sub-surface porous structure of (100) n-InP following anodization in 1 - 10 mol dm-3 aqueous KOH were studied using linear sweep voltammetry (LSV) in combination with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). LSV of n-InP in 10 mol dm-3 KOH showed a single anodic current peak at 0.41 V. As the concentration of electrolyte was decreased, the peak increased in current density and charge and shifted to more positive potentials; eventually individual peaks were no longer discernable. Porous layers were observed in SEM cross-sections following linear potential sweeps and the porous layer thickness increased significantly with decreasing KOH concentration, reaching a maximum value at ~2.2 mol dm-3. At concentrations less than 1.8 mol dm-3 the layer thickness decreased sharply, pore diameters became wider and pore walls became narrower until eventually, at 1.1 mol dm-2 or lower, no porous layers were observed. It was also observed that the pore width increased and the inter-pore spacing decreased with decreasing concentration. It is proposed that preferential pore propagation occurs along <111> directions, contrary to previous suggestions, and that the resulting anoporous domains, initially formed, have triangular cross-sections when viewed in one of the {110} cleavage planes, ‘dove-tail’ crosssections viewed in the orthogonal {110} cleavage plane and square profiles when viewed in the (100) plane of the electrode surface.
Keyword(s): Electrolyte concentration; Surface morphology; Anodization; Aqueous KOH; Linear sweep voltammetry (LSV); Scanning electron microscopy (SEM); Transmission electron microscopy (TEM); Electrochemistry
Publication Date:
Type: Journal article
Peer-Reviewed: Yes
Language(s): English
Institution: University College Cork
Funder(s): Science Foundation Ireland
Citation(s): Lynch, R., O'Dwyer, C., Buckley, D. N., Sutton, D., Newcomb, S. B. (2006) 'Effect of Electrolyte Concentration on Anodic Nanoporous Layer Growth for n-InP in Aqueous KOH. ECS Transactions 2(5): 131-141; doi:10.1149/1.2204886
Publisher(s): Electrochemical Society
File Format(s): application/pdf
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First Indexed: 2013-02-28 05:33:35 Last Updated: 2016-10-14 06:29:50