Formation of nanoporous InP by electrochemical anodization

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Date
2004-01
Authors
Buckley, D. Noel
O'Dwyer, Colm
Lynch, Robert P.
Newcomb, Simon B.
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The Electrochemical Society
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Research Projects
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Abstract
Porous InP layers can be formed electrochemically on (100) oriented n- InP substrates in aqueous KOH. A nanoporous layer is obtained underneath a dense near-surface layer and the pores appear to propagate from holes through the near-surface layer. In the early stages of the anodization transmission electron microscopy (TEM) clearly shows individual porous domains which appear to have a square-based pyramidal shape. Each domain appears to develop 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. When the domains grow, the current density increases correspondingly. Eventually, the domains meet forming a continuous porous layer, 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. Numerical models of this process have been developed. Current-time curves at constant potential exhibit a peak and porous layers are observed to form beneath the electrode surface. The density of pits formed on the surface increases with time and approaches a plateau value.
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Keywords
Porous InP layers , InP substrates , Aqueous KOH , Transmission electron microscopy (TEM) , AFM measurement
Citation
Buckley, D. N., O’Dwyer, C., Lynch, R., Sutton, D., Newcomb, S. B. (2004) 'Formation of Nanoporous InP by Electrochemical Anodization', 206th Meeting of the Electrochemical Society: State -of-the-Art Program on Compound Semiconductors XLI. Hilton Hawaiian Village, Honolulu, Hawaii, 3-8 October. Pennington, NJ: The Electrochemical Society, 6, pp. 103-117.
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© The Electrochemical Society, Inc. 2004. 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 Buckley, D. N., O’Dwyer, C., Lynch, R., Sutton, D., Newcomb, S. B. (2004) 'Formation of Nanoporous InP by Electrochemical Anodization', 206th Meeting of the Electrochemical Society: State -of-the-Art Program on Compound Semiconductors XLI. Hilton Hawaiian Village, Honolulu, Hawaii, 3-8 October. Pennington, NJ: The Electrochemical Society, 6, pp. 103-117.