(Invited) electrochemical formation of nanoporous indium phosphide In KOH electrolytes

D. Noel Buckley, Nathan Quill, Colm O'Dwyei, Robert P. Lynch

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

Abstract

Anodization of highly doped n-InP in KOH can result in a nanoporous sub-surface layer. Pores originate from surface pits and an isolated porous domain is initially formed beneath each pit. Domains are separated from the surface by a thin non-porous layer and each is connected to the electrolyte by its pit. Pores emanate along the <111>A directions to form truncated tetrahedral domains. We propose a three-step model of electrochemical pore formation: (1) hole generation at pore tips, (2) hole diffusion and (3) electrochemical oxidation of the semiconductor to form etch products. Step 1 determines the overall etch rate. However, if the kinetics of Step 3 are slow relative to Step 2, then etching can occur at preferred crystallographic sites leading to pore propagation in preferential directions. Pore width decreases with increasing anodization temperature and with increasing KOH concentration up to 9 mol dm-3, above which it decreases. At low current densities pores have sharp tips and triangular cross-sections; at higher current densities, the pore tips and cross-sections become more rounded while the pore width decreases. These observations are explained by the three-step model.

Original languageEnglish
Title of host publicationECS Transactions
EditorsP. Granitzer, R. Boukherroub, D.J. Lockwood, H. Masuda, S. Virtanen
PublisherElectrochemical Society Inc.
Pages15-35
Number of pages21
Edition1
ISBN (Electronic)9781607688457
ISBN (Print)9781510871618
DOIs
Publication statusPublished - 2018
EventSymposium on Pits and Pores 8: Nanomaterials - Fabrication, Properties, and Applications - AiMES 2018, ECS and SMEQ Joint International Meeting - Cancun, Mexico
Duration: 30 Sep 20184 Oct 2018

Publication series

NameECS Transactions
Number1
Volume86
ISSN (Print)1938-6737
ISSN (Electronic)1938-5862

Conference

ConferenceSymposium on Pits and Pores 8: Nanomaterials - Fabrication, Properties, and Applications - AiMES 2018, ECS and SMEQ Joint International Meeting
Country/TerritoryMexico
CityCancun
Period30/09/184/10/18

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