(Invited) development of nanoporous structures and oscillatory behavior during anodization of n-InP in alkaline electrolytes

D. N. Buckley, N. Quill, C. O'Dwyer, T. Melly, E. Harvey, R. P. Lynch

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In the early stages of anodization of n-InP in KOH, isolated nanoporous domains form and eventually merge into a continuous layer. SEM and TEM cross-sections show clear evidence that these have the shape of truncated tetrahedrons and result from preferential pore progagation along the <111>A directions. We propose a three-step model of electrochemical nanopore formation that explains how crystallographically oriented etching can occur even though the rate-determining process occurs only at pore tips. The rate-determining Step 1 is the generation of holes at pore tips. If Step 2 (hole diffusion) is faster than Step 3 (electrochemical reaction) then etching can occur at preferred crystallographic sites, such as phosphorus dangling bonds, leading to pore propagation in preferential directions. Well-defined oscillations are observed under certain conditions when n-InP is anodized in either KOH or (NH4)2S. The oscillations in (NH4)2S, have a symmetric profile and the charge per cycle remains constant over a wide range of conditions: we propose a mechanism based on cyclical changes in the morphology of the InP surface beneath an In2S3 film. The exact mechanism of the oscillatory behavior in KOH is still unclear.

Original languageEnglish
Title of host publicationPRiME 2020
Subtitle of host publicationPits and Pores 9: Nanomaterials - Fabrication, Properties, and Applications
EditorsP. Granitzer, D. Lockwood, H. Habazaki, S. Virtanen, H. Imahori
PublisherIOP Publishing Ltd
Pages89-106
Number of pages18
Edition2
ISBN (Electronic)9781607688976
DOIs
Publication statusPublished - 2020
EventPacific Rim Meeting on Electrochemical and Solid State Science 2020, PRiME 200 - Honolulu, United States
Duration: 4 Oct 20209 Oct 2020

Publication series

NameECS Transactions
Number2
Volume98
ISSN (Print)1938-6737
ISSN (Electronic)1938-5862

Conference

ConferencePacific Rim Meeting on Electrochemical and Solid State Science 2020, PRiME 200
Country/TerritoryUnited States
CityHonolulu
Period4/10/209/10/20

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