Type

Journal Article

Authors

Simon B. Newcomb
M. Serantoni
David Sutton
D. Noel Buckley
Colm O'Dwyer

Subjects

Chemistry

Topics
voltammetry chemical analysis porous semiconductors anodes electrochemical electrodes etching atomic force microscopy surface structure ellipsometry porosity iii v semiconductors indium compounds carrier density nanoporous materials transmission electron microscopy

An investigation by AFM and TEM of the mechanism of anodic formation of nanoporosity in n-InP in KOH (2006)

Abstract The early stages of nanoporous layer formation, under anodic conditions in the absence of light, were investigated for n-type InP with a carrier concentration of ∼3× 1018 cm-3 in 5 mol dm-3 KOH and a mechanism for the process is proposed. At potentials less than ∼0.35 V, spectroscopic ellipsometry and transmission electron microscopy (TEM) showed a thin oxide film on the surface. Atomic force microscopy (AFM) of electrode surfaces showed no pitting below ∼0.35 V but clearly showed etch pit formation in the range 0.4-0.53 V. The density of surface pits increased with time in both linear potential sweep and constant potential reaching a constant value at a time corresponding approximately to the current peak in linear sweep voltammograms and current-time curves at constant potential. TEM clearly showed individual nanoporous domains separated from the surface by a dense ∼40 nm InP layer. It is concluded that each domain develops as a result of directionally preferential pore propagation from an individual surface pit which forms a channel through this near-surface layer. As they grow larger, domains meet, and the merging of multiple domains eventually leads to a continuous nanoporous sub-surface region.
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Full list of authors on original publication

Simon B. Newcomb, M. Serantoni, David Sutton, D. Noel Buckley, Colm O'Dwyer

Experts in our system

1
D. Noel Buckley
University College Cork
Total Publications: 27
 
2
Colm O'Dwyer
University College Cork
Total Publications: 121