Pulsed Anodization for Control of Porosity Gradients and Interface Roughness in Porous Silicon

Timothy James, Adrian Keating, Giacinta Parish, Charles Musca

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

We present a technique involving the use of pulsed anodization for porous silicon (PS) thin-film fabrication on low doped substrates, for which the interface roughness and porosity gradients usually observed in such films can be eliminated. The work presented includes a detailed characterization of the effects of duty cycle and frequency during pulsed anodization. The study spans pulsing frequencies of 0.1–1000 Hz and duty cycles of 5–50%. The combination of low frequency (0.1 Hz) and low duty cycle (5%) for the pulse train used for anodization produces PS thin films, displaying no measurable interface roughness or porosity gradient. The mechanisms behind the wide variation in available PS thin-film properties with pulsed anodization parameters are analyzed using a galvanostatic technique. The analysis indicates that the inhomogeneity and roughness observed in PS films fabricated on low doped starting wafers are both due to the unstable multistep dissolution kinetics of silicon during PS film formation.
Original languageEnglish
Pages (from-to)H744-H750
JournalJournal of the Electrochemical Society
Volume156
Issue number9
DOIs
Publication statusPublished - 2009

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