Process of Formation of Porous Layers in n-InP

Quill, Nathan; Clancy, Ian; Nakahara, S.; Belochapkine, Serguei; O’Dwyer, Colm; Buckley, D. H.; Lynch, Robert P.

doi:10.1149/07704.0067ecst

Cited by 8 publications

(13 citation statements)

References 19 publications

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“…Nanoporous structures can be formed in compound semiconductors by anodic etching under either acidic or alkaline conditions. In this paper, we will review our recent work 13,16,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] on n-InP in aqueous KOH.…”

Section: Introductionmentioning

confidence: 99%

(Invited) Electrochemical Formation of Nanoporosity in n-InP Anodes in KOH

Buckley¹,

O’Dwyer²,

Lynch³

et al. 2011

ECS Trans.

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We review our recent work on anodic formation of nanoporosity in n-InP in aqueous KOH. Typically, a nanoporous sub-surface region is formed beneath a thin, dense near-surface layer. Atomic force microscopy (AFM) shows pit formation on the surface in the earlier stages of etching, and transmission electron microscopy (TEM) shows individual nanoporous domains separated from the surface by a thin InP layer. Each domain develops from a surface pit. We developed a model based on propagation of pores along the <111>A directions. The model predicts porous domains with a truncated tetrahedral shape and this was confirmed by scanning electron microscopy (SEM) and TEM. Pores are cylindrical and have well-developed facets only near their tips. No porous layers are observed at a KOH concentration of 1.1 mol dm -2 or lower. Linear sweep voltammograms (LSVs) show a pronounced anodic peak corresponding to the formation of the porous region. We describe a technique to deconvolute the effects of potential and time in LSVs and explain their shape and their relationship to porous layer formation.

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Section: Introductionmentioning

confidence: 99%

(Invited) Electrochemical Formation of Nanoporosity in n-InP Anodes in KOH

Buckley¹,

O’Dwyer²,

Lynch³

et al. 2011

ECS Trans.

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“…Thus, at low temperatures, peak P 1 in Fig. 2a (which corresponds to domain merging) 66 occurs at a low layer thickness Figure 9. Plot of (a) pore width ( ) (from Fig.…”

Section: Effect Of Temperature On Surface Pitting and Layer Thickness-mentioning

confidence: 96%

“…A detailed analysis of how the progression of porous etching in InP in KOH relates to the features of LSVs is given elsewhere. 66 Each surface pit leads to a porous domain and so, when the areal density of pits is high, domains are numerous and consequently will have grown only to a small size when they merge, i.e. when they begin to restrict each other's lateral growth.…”

Section: Effect Of Temperature On Surface Pitting and Layer Thickness-mentioning

confidence: 99%

Anodic Formation of Nanoporous Indium Phosphide in KOH Electrolytes: Effects of Temperature and Concentration

Quill

Buckley

O’Dwyer

et al. 2019

J. Electrochem. Soc.

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Anodization of n-InP electrodes was carried out over a range of temperatures and KOH concentrations. Scanning electron microscopy showed <111>A aligned pore growth with pore width decreasing as the temperature was increased. This variation is explained in terms of the relative rates of electrochemical reaction and hole diffusion and supports the three-step model proposed earlier. As temperature is increased, both the areal density and width of surface pits decrease resulting in a large increase in the current density through the pits. This explains an observed decrease in porous layer thickness: pits sustain mass transport at the necessary rate for a shorter time before precipitation of etch products blocks the pores. As the concentration of KOH is increased, both pore width and layer thickness decrease to minima at ∼9 mol dm −3 after which they again increase. This variation of pore width is also explained by the three-step model and the variation in layer thickness is explained by mass transport effects. Layer porosity follows a similar trend to pore width, further supporting the three-step model. A transition from porous layer formation to planar etching is observed below 2 mol dm −3 KOH, and this is also explained by the three-step model.

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“…We have previously described how each feature of the LSV corresponds to a particular stage during the formation of a porous layer at the InP surface. 27,34,43 Here we shall mention only the pitting potential; so called because it is the potential at which etch pits start to appear on the electrode surface. 42 On an LSV, the pitting potential is the potential at which a significant current begins to flow through the electrode.…”

Section: Variation Of Pore Width With Carrier Concentrationmentioning

confidence: 99%

“…The list of semiconductors that can now be rendered porous electrochemically includes germanium, [6][7][8] GaP, [9][10][11] InP, [12][13][14][15][16][17] GaAs, [18][19][20][21][22] GaN, [23][24][25] and many others. A range of different porous structures can be obtained in these semiconductors by variation of electrolyte type and concentration, 14,26 carrier concentration and substrate orientation, 27,28 as well as the current density or potential at which the porous structures are formed. 29,30 This wide range of porous structures have most often been characterised in terms of their morphology.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Pore Formation in InP: Understanding and Controlling Pore Morphology

et al. 2017

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Pores formed anodically in InP at different temperatures, electrolyte (KOH) concentrations, carrier concentrations and current densities exhibit significant pore width variations. The pore width decreases as the temperature, carrier concentration or current density are increased. The pore width also decreases when the KOH concentration is increased up to 9 mol dm -3 , but increases slightly as the concentration is increased further. These pore width variations are explained by a three-step model for pore formation based on competition in kinetics between the different steps in the etching mechanism. The variation of pore width with current density is explained explicitly in terms of the crystallographic etching mechanism and this is supported by observation of the different crystallographic features of the pore cross section at different current densities.

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Process of Formation of Porous Layers in n-InP

Cited by 8 publications

References 19 publications

(Invited) Electrochemical Formation of Nanoporosity in n-InP Anodes in KOH

(Invited) Electrochemical Formation of Nanoporosity in n-InP Anodes in KOH

Anodic Formation of Nanoporous Indium Phosphide in KOH Electrolytes: Effects of Temperature and Concentration

Electrochemical Pore Formation in InP: Understanding and Controlling Pore Morphology

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