Electrochemical Formation of Ordered Pore Arrays in InP in KCl

Quill, Nathan; Lynch, Robert P.; O’Dwyer, Colm; Buckley, D. H.

doi:10.1149/05006.0377ecst

Cited by 13 publications

(20 citation statements)

References 31 publications

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“…Nanopore formation due to electrochemical etching occurs in a range of semiconductors from Si to InP [2][3][4][5][6][7][8][9] and it is quite common for such pores to propagate along preferential directions. These directions and the pore morphology have been shown to be affected by a range of parameters including temperature, 10 composition 11,12 and concentration 13 of electrolyte, and type, 14 orientation 15 and doping density 16 of the substrate.…”

Section: Introductionmentioning

confidence: 99%

Propagation of nanopores during anodic etching of n-InP in KOH

Lynch

Quill

O’Dwyer

et al. 2013

Phys. Chem. Chem. Phys.

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We propose a three-step model of electrochemical nanopore formation in n-InP in KOH that explains how crystallographically oriented etching can occur even though the rate-determining process (hole generation) occurs only at pore tips. The model shows that competition in kinetics between hole diffusion and electrochemical reaction determines the average diffusion distance of holes along the semiconductor surface and this, in turn, determines whether etching is crystallographic. If the kinetics of reaction are slow relative to diffusion, etching can occur at preferred crystallographic sites within a zone in the vicinity of the pore tip, leading to pore propagation in preferential directions. Symmetrical etching of three {111}A faces forming the pore tip causes it to propagate in the (remaining) [111]A direction. As a pore etches, propagating atomic ledges can meet to form sites that can become new pore tips and this enables branching of pores along any of the [111]A directions. The model explains the observed uniform width of pores and its variation with temperature, carrier concentration and electrolyte concentration. It also explains pore wall thickness, and deviations of pore propagation from the [111]A directions. We believe that the model is generally applicable to electrochemical pore formation in III-V semiconductors.

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Section: Introductionmentioning

confidence: 99%

Propagation of nanopores during anodic etching of n-InP in KOH

Lynch

Quill

O’Dwyer

et al. 2013

Phys. Chem. Chem. Phys.

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Section: 10mentioning

confidence: 99%

“…14,15 It has been recently demonstrated that porous dissolution can also be achieved at neutral solution in presence of Cl − . 16,17 Finally, a nucleophilic substitution mechanism has been proposed to explain the pore growth on III-V crystals.18-20 It demonstrates that both physical and chemical models must be considered when dealing with porous etching.Investigations on the chemical, electrochemical and photoelectrochemical uniform etching of InP have led to various possible mechanisms. Although 6 or 8 charge mechanisms are usually admitted, the dissolution valence analytically determined by measuring the indium ion concentration in the etching solution, using atomic absorption spectroscopy (AAS) or inductively coupled plasma emission spectrometry (ICP-ES), varies from 3 to 12.…”

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confidence: 99%

Investigations of the Anodic Porous Etching of n-InP in HCl by Atomic Absorption and X-ray Photoelectron Spectroscopies

Santinacci

Bouttemy

Petit

et al. 2018

J. Electrochem. Soc.

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The electrochemical porous etching of n-InP in 1 M HCl has been investigated by monitoring the mass of In 3+ released during and after the anodic polarization. The study has been performed on both crystal-oriented (CO) and current line-oriented (CLO) pores grown at 10 mA·cm −2 and 5 V vs Ag/AgCl. An unexpected evolution of the mass of In 3+ has been measured when the electrochemical dissolution process is stopped. It indicates a mass loss more than twice higher after 2 or 3 hours. This demonstrates that the accurate amount of dissolved InP must be considered a longtime after the end of the polarization. The comparisons of the etched masses for CO and CLO pores with the values calculated from the coulometric charges indicate that the etching processes are similar for the two pore geometries and that the dissolution valence for InP is 2. The chemical analyses, performed by X-ray photoelectron spectroscopy, reveal that the main corrosion products are Cl-containing compounds such as InCl 3 . This gives valuable information to confirm an InP porous etching mechanism proposed earlier in literature. Likewise other one-dimensional nanostructures, electrochemically grown porous semiconductors have become an attractive field of interest. Though numerous attempts to understand the pore formation have been carried out, crucial mechanistic parameters such as the dissolution valence (z) are still not clarified for III-V compounds since most of the studies refer to the porous etching of Si.1 Gravimetric investigations have pointed out different z during electropolishing and pore formation on Si.2 The dissolution valence is 4 (the expected value since Si is a tetravalent element) during electropolishing and it does not depend on the applied current density ( j), the doping or the electrolyte concentration (c). Conversely, z varies, from 2 to 4, with those parameters during porous etching. Furthermore, the dissolution valence during the pore growth can be 4 at the tips and 2 on the walls. 3 It illustrates that porous dissolution process is a tricky phenomenon and it is different from uniform polishing.The pore growth mechanisms reported in literature can be divided in two families: "chemical" and "physical" models. The latter are based on the charge carrier distribution at the semiconductor/electrolyte interface and can basically be applied to any semiconductor since no chemical aspects are considered. However strong differences are observed between Si, which is an elemental semiconductor, and III-V compounds or between III-V materials themselves. 4 Thus chemical aspects must also be considered to depict accurately the porous dissolution of such materials. The peculiar dissolution along 111 B directions leading to crystal-oriented (CO) pores in GaP, GaAs and InP (with B referring to the second element for A-B compounds, e. g. P in InP and GaP) [5][6][7] or the catacomb-like pore morphology observed solely on GaP 8 emphasizes the influence of the chemical nature of the semiconductors on the pore growth. The chemical aspect of the...

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“…Nanopore formation due to electrochemical etching has been demonstrated in a range of semiconductors from Si to InP(1-12). The morphology of these porous layers can vary wildly between different semiconductors (13), and for an individual semiconductor with the variation of temperature (14), composition (15,16) and concentration (17) of electrolyte, and orientation (18) and doping density (19) of the substrate. Many different pore morphologies have been observed and several models have been proposed (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32) to explain them.…”

Section: Introductionmentioning

confidence: 99%

“…We have previously investigated (14,15,(33)(34)(35)(36)(37)(38)(39) the early stages of pore formation in InP in aqueous KOH electrolytes. Pores originate from etch pits in the electrode surface and propagate along <111>A directions to form porous domains beneath a thin dense (i.e.…”

Section: Introductionmentioning

confidence: 99%