Microstructure and formation mechanism of porous silicon

Beale, M.I.J.; Chew, N. G.; Uren, Michael J.; Cullis, A. G.; Benjamin, J. D.

doi:10.1063/1.95807

Cited by 253 publications

(108 citation statements)

References 2 publications

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“…For a (001)-oriented PS sample, it is generally admitted that the pores have a cylindrical shape with lateral branching (Beale et al, 1985). The long axis of the cylindrical shape is parallel to the h001i direction, i.e.…”

Section: Study Of Thick Ps Layersmentioning

confidence: 99%

“…There are still some controversies regarding the pore size and morphology, and more particularly concerning the pore-propagation direction, which is the result of a competition between the current-¯ow direction and the crystallographic directions. In 1985, in a cross-sectional transmission electron microscopy (XTEM) study on p + -and p À -type (respectively highly and slightly boron-doped) PS layers, Beale et al (1985) showed pore propagation perpendicular to the wafer surface, i.e. along the current direction.…”

Section: Introductionmentioning

confidence: 99%

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Structural properties ofp⁺-type porous silicon layersversusthe substrate orientation: an X-ray diffraction comparative study

Faivre

Bellet

1999

J Appl Cryst

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The structural properties of (001)-and (111)-oriented p + -type porous silicon samples have been investigated using X-ray techniques. X-ray re¯ectivity applied to thin layers of both orientations allows the estimation of the layer thickness, the porosity and the interface roughness. High-resolution X-ray diffraction was used to obtain symmetrical and asymmetrical rocking curves, as well as maps of the reciprocal space. The lattice-mismatch parameter was measured and some indications about the pore shape, orientation and size were deduced. The obtained X-ray curves as well as differential scanning calorimetry data are compared to discuss the in¯uence of the substrate orientation on the structural properties of p + -type porous silicon material.

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Section: Study Of Thick Ps Layersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural properties ofp⁺-type porous silicon layersversusthe substrate orientation: an X-ray diffraction comparative study

Faivre

Bellet

1999

J Appl Cryst

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“…This argument was supported in the literature, from the chemical composition studies of PS layer, using IR spectroscopy measurements showing that the silicon surface is terminated with hydrogen, although the Si-F (6 eV) bond is much strong than Si-H bond. 7,12,14,[18][19][20][21][22][23][24] Figure 1 shows top view images of typical PS samples prepared by photoelectrochemical oxidation of n-type silicon, etching time of 60 min and current density of 11 mA cm -2 . The samples were prepared with two different solutions of HF-ethanol and HF-MeCN, for two types of Si resistivity.…”

Section: Resultsmentioning

confidence: 99%

Morphological and optical characteristics of porous silicon produced by anodization process in HF-acetonitrile and HF-ethanol solutions

Miranda¹,

Baldan²,

Beloto³

et al. 2008

J. Braz. Chem. Soc.

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Amostras de silício poroso (PS) foram obtidas pelo processo de anodização em lâminas de Si tipo n, dopadas com fósforo. A oxidação eletroquímica do PS foi obtida utilizando-se solução de ácido fluorídrico (HF) contendo aditivos como etanol e acetonitrila (MeCN). A formação dos poros foi estudada com a variação da resistividade das laminas de Si e parâmetros de processo como: concentração do ácido, densidade de corrente e tempo de anodização. As técnicas de Microscopia Eletrônica de Varredura (MEV) e Espectroscopia de Espalhamento Raman foram utilizadas para a investigação da morfologia e fotoluminescência, respectivamente. A camada de PS formada com o uso da solução de HF-MeCN mostrou maior uniformidade e homogeneidade na distribuição dos macroporos com diferentes tipos e tamanhos. Esse comportamento pode ser explicado devido a tensão superficial da MeCN ser maior que a do etanol. Consequentemente, as moléculas de MeCN podem passivar a superfície do silício durante o processo de anodização.Porous silicon (PS) samples were obtained by anodization etching process of n-type silicon wafer phosphorus-doped. Electrochemical oxidation of PS was investigated in aqueous hydrofluoric acid (HF) containing additive such as ethanol or acetonitrile. Pore formation was studied with the variation of type and resistivity of the silicon wafer, taking into account the most important anodization process parameters such as: acid concentration, current density and anodization time. Scanning Electron Microscopy (SEM) and Raman Scattering Spectroscopy measurements were used to characterize the macropore morphology changes and sample photoluminescense responses, respectively. PS layer formed in HF-acetonitrile solution showed more uniform and homogeneous macropore distributions with different shapes and sizes. Behavior may be explained because acetonitrile surface tension is greater than that of ethanol. Therefore, acetonitrile molecules might passivate the silicon surface dissolved during the anodization process. Keywords: porous silicon, HF-acetonitrile, HF-ethanol IntroductionSince the discovery of its visible photoluminescence (PL) at room temperature, porous silicon (PS) has been intensively studied. Nowadays, PS is considered a very attractive material for the sensing layer in a chemical sensor, sacrificial layer in micromachining, and light emitting diode (LED) in optoelectronic devices. [1][2][3][4] Porous Si might be formed by electrochemical etching of single monocrystalline Si in HF solutions containing additives as ethanol or acetonitrile (MeCN). However, the anodization process was firstly studied by Bomchil et al., 5 in 1983, using HF and ethanol solution and they reported that ethanol improved the homogeneity of PS layer. Consequently, HF-ethanol has been used by most research groups as the standard electrolyte for PS formation process. After that, Propst et al. 6 have reported the electrochemical oxidation of p-and n-type silicon in nonaqueous electrolyte of HF-MeCN and discussed their singular and large porous structure...

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“…It was in order to make a detailed study of models proposed to explain the morphology found in n-type silicon (Smith et ai. 1988, Beale et al 1985a, b, Erlebacher et al 1994, including the formation of side branches and the reaction of the system to changes in the applied potential, that we decided to examine the pore formation process in real time.…”

Section: Anodic Etching Of Siliconmentioning

confidence: 99%

Dynamic observation of electrochemical etching in silicon

Ross

Searson

1995

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This rcpon has becn reprodud directly from &e bsc availabk copy.Lawrence Berkeley Laboratory is an equal opportunity employer. DISCLAIMER ABSTRACT:We have designed and constructed a "EM specimen holder in order to observe the process of pore formation in silicon. The holder incorporates electricaI feedthroughs and a sealed reservoir for the electrolyte and accepts lithographically patterned silicon specimens. We describe the system and present preliminary, ex situ observations of the etching process.

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Microstructure and formation mechanism of porous silicon

Cited by 253 publications

References 2 publications

Structural properties ofp⁺-type porous silicon layersversusthe substrate orientation: an X-ray diffraction comparative study

Structural properties ofp⁺-type porous silicon layersversusthe substrate orientation: an X-ray diffraction comparative study

Morphological and optical characteristics of porous silicon produced by anodization process in HF-acetonitrile and HF-ethanol solutions

Dynamic observation of electrochemical etching in silicon

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Microstructure and formation mechanism of porous silicon

Cited by 253 publications

References 2 publications

Structural properties ofp+-type porous silicon layersversusthe substrate orientation: an X-ray diffraction comparative study

Structural properties ofp+-type porous silicon layersversusthe substrate orientation: an X-ray diffraction comparative study

Morphological and optical characteristics of porous silicon produced by anodization process in HF-acetonitrile and HF-ethanol solutions

Dynamic observation of electrochemical etching in silicon

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Structural properties ofp⁺-type porous silicon layersversusthe substrate orientation: an X-ray diffraction comparative study

Structural properties ofp⁺-type porous silicon layersversusthe substrate orientation: an X-ray diffraction comparative study