A mechanistic study of anodic formation of porous InP
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Date
2003-01
Authors
O'Dwyer, Colm
Buckley, D. Noel
Sutton, David
Newcomb, Simon B.
Serantoni, M.
Journal Title
Journal ISSN
Volume Title
Publisher
The Electrochemical Society
Published Version
Abstract
When porous InP is anodically formed in KOH electrolytes, a thin layer ~40
nm in thickness, close to the surface, appears to be unmodified. We have
investigated the earlier stages of the anodic formation of porous InP in 5
mol dm-3 KOH. TEM clearly shows individual porous domains which
appear triangular in cross-section and square in plan view. The crosssections
also show that the domains are separated from the surface by a ~40
nm thick, dense InP layer. It is concluded that the porous domains have a
square-based pyramidal shape and that each one develops from an individual
surface pit which forms a channel through this near-surface layer. We
suggest that the pyramidal structure arises as a result of preferential pore
propagation along the <100> directions. AFM measurements show that the
density of surface pits increases with time. Each of these pits acts as a
source for a pyramidal porous domain, and these domains eventually form a
continuous porous layer. This implies that the development of porous
domains beneath the surface is also progressive in nature. Evidence for this
was seen in plan view TEM images. Merging of domains continues to
occur at potentials more anodic than the peak potential, where the current is
observed to decrease. When the domains grow, the current density increases
correspondingly. Eventually, domains meet, the interface between the
porous and bulk InP becomes relatively flat and its total effective surface
area decreases resulting in a decrease in the current density. Quantitative
models of this process are being developed.
Description
Keywords
Porous InP , KOH electrolytes , Anodic formation , AFM measurement , TEM image
Citation
O’ Dwyer, C., Buckley, D. N., Sutton, D., Newcomb, S. B., Seratoni, M. (2003) 'A Mechanistic Study of Anodic Formation of Porous InP’, 203rd Meeting of the Electrochemical Society: InP Electrochemistry. Palais des Congres de Paris, Paris, France, 27 April – 2 May. Pennington, NJ: The Electrochemical Society, 4, pp. 63-72.
Link to publisher’s version
Copyright
© The Electrochemical Society, Inc. 2003. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in O’ Dwyer, C., Buckley, D. N., Sutton, D., Newcomb, S. B., Seratoni, M. (2003) 'A Mechanistic Study of Anodic Formation of Porous InP’, 203rd Meeting of the Electrochemical Society: InP Electrochemistry. Palais des Congres de Paris, Paris, France, 27 April – 2 May. Pennington, NJ: The Electrochemical Society, 4, pp. 63-72.