Formation of Straight 10 nm Diameter Silicon Nanopores in Gold Decorated Silicon

Büttner, Claudia; Langner, Andreas; Geuss, Markus; Müller, Frank; Werner, P.; Gösele, U.

doi:10.1021/nn900817d

Cited by 12 publications

(15 citation statements)

References 20 publications

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“…The black hemisphere on the Si-NW tip represents the gold catalyst dot. It is evident that no Au dots are present on the Si-NW sidewall, contrary to what was reported in some other works [47]. In that case, Au agglomeration was attributed to the presence of a thin layer of gold covering the Si-NWs formed because of the high temperature of molecular beam epitaxy process (525 °C), which disintegrates in tiny gold clusters during final cooling.…”

Section: Resultscontrasting

confidence: 61%

Study on the Physico-Chemical Properties of the Si Nanowires Surface

et al. 2019

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Silicon nanowires (Si-NWs) have been extensively studied for their numerous applications in nano-electronics. The most common method for their synthesis is the vapor–liquid–solid growth, using gold as catalyst. After the growth, the metal remains on the Si-NW tip, representing an important issue, because Au creates deep traps in the Si band gap that deteriorate the device performance. The methods proposed so far to remove Au offer low efficiency, strongly oxidize the Si-NW sidewalls, or produce structural damage. A physical and chemical characterization of the as-grown Si-NWs is presented. A thin shell covering the Au tip and acting as a barrier is found. The chemical composition of this layer is investigated through high resolution transmission electron microscopy (TEM) coupled with chemical analysis; its formation mechanism is discussed in terms of atomic interdiffusion phenomena, driven by the heating/cooling processes taking place inside the eutectic-Si-NW system. Based on the knowledge acquired, a new efficient etching procedure is developed. The characterization after the chemical etching is also performed to monitor the removal process and the Si-NWs morphological characteristics, demonstrating the efficiency of the proposed method and the absence of modifications in the nanostructure.

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Section: Resultscontrasting

confidence: 61%

Study on the Physico-Chemical Properties of the Si Nanowires Surface

et al. 2019

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“…The widespread explanation of the molecular hydrogen formation resulted from a divalent reaction process [17,21,34,[36][37][38][39][40][41][42][43][44][45][46][47][48][49] in combination with the hydrogen-free reaction process during tetravalent valence transfer [11,12,15,21,34,40,41,44,55] may still fit, to some extent, based on the findings of example 2 of silver deposition. The results of the other metal depositions explained in Sections 3.2-3.4, especially the findings of platinum deposition, support a different and more complex theory for molecular hydrogen formation.…”

Section: Silver Deposition Onto Multicrystalline Siliconmentioning

confidence: 99%

“…Several series of experiments have been carried out based on HF solutions with Ag + , Cu 2+ , AuCl 4 − or PtCl 6 2− and multicrystalline silicon. The metal ions were chosen because they are commonly used in the metal-assisted etching of silicon [7][8][9][10][11][12][13][14][15][16][18][19][20][21][22][23][24]26,27,[29][30][31][32][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]63,[67][68][69][70][71][72][73][74]…”

Section: Introductionmentioning

confidence: 99%

The Role of the Molecular Hydrogen Formation in the Process of Metal-Ion Reduction on Multicrystalline Silicon in a Hydrofluoric Acid Matrix

Schönekerl

Acker

2021

Nanomaterials

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Metal deposition on silicon in hydrofluoric acid (HF) solutions is a well-established process for the surface patterning of silicon. The reactions behind this process, especially the formation or the absence of molecular hydrogen (H2), are controversially discussed in the literature. In this study, several batch experiments with Ag+, Cu2+, AuCl4– and PtCl62– in HF matrix and multicrystalline silicon were performed. The stoichiometric amounts of the metal depositions, the silicon dissolution and the molecular hydrogen formation were determined analytically. Based on these data and theoretical considerations of the valence transfer, four reasons for the formation of H2 could be identified. First, H2 is generated in a consecutive reaction after a monovalent hole transfer (h+) to a Si–Si bond. Second, H2 is produced due to a monovalent hole transfer to the Si–H bonds. Third, H2 occurs if Si–Si back bonds of the hydrogen-terminated silicon are attacked by Cu2+ reduction resulting in the intermediate species HSiF3, which is further degraded to H2 and SiF62–. The fourth H2-forming reaction reduces oxonium ions (H3O+) on the silver/, copper/ and gold/silicon contacts via monovalent hole transfer to silicon. In the case of (cumulative) even-numbered valence transfers to silicon, no H2 is produced. The formation of H2 also fails to appear if the equilibrium potential of the 2H3O+/H2 half-cell does not reach the energetic level of the valence bands of the bulk or hydrogen-terminated silicon. Non-hydrogen-forming reactions in silver, copper and gold deposition always occur with at least one H2-forming process. The PtCl62– reduction to Pt proceeds exclusively via even-numbered valence transfers to silicon. This also applies to the reaction of H3O+ at the platinum/silicon contact. Consequently, no H2 is formed during platinum deposition.

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“…From the derivations, we can know that this APS growth kinetics is a resultant phenomenon of complex interlinked (Table 1) 39 is due to the prominent diffusivity and reactivity of the defect site. To describe the DMPS development kinetics we consider a simple defective structure, one-dimensionally propagated and regarded as an equivalent defect state through its length, 69 which is placed on an intermediate stage of defect removal as shown in Figure 6.…”

Section: Analytical Modelingmentioning

confidence: 99%

Experimentally Derived Catalytic Etching Kinetics for Defect-Utilized Dual-Porous Silicon Formation

2012

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A kinetic model of defect-utilized dual-porous structure (DPS) formation of silicon, composed of amorphous porous structure (APS) and defect-followed mesoporous structure (DMPS), is proposed. It is found that a defect site is preferentially removed while creating the oblique DMPS of high aspect ratio, and the DMPS is wholly covered with the APS which is gradually grown through applied etching time but finally saturated. It is suggested that the APS growth is progressed by the chemically enhanced-oxygen diffusion, which is driven by catalytic chemical reactions, and the APS dissolution depends on the oxygen concentration of the APS itself. On the basis of these results, we describe the DPS formation using fundamental reaction kinetics and Fick's law of diffusion. Understanding the APS growth mechanism is profound and potentially useful for prediction and controlling of the porous Si growth in the conventional HF/HNO 3 /H 2 O etching system. The DMPS development at the defect sites is ca. 22 times faster than the defect-free sites due to varied physicochemical properties. This analytical approach is a new attempt to describe the porous silicon formation mechanism as well as the conventional HF/HNO 3 /H 2 O etching procedure and further opens a new domain for the viability of defect engineering.

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Formation of Straight 10 nm Diameter Silicon Nanopores in Gold Decorated Silicon

Cited by 12 publications

References 20 publications

Study on the Physico-Chemical Properties of the Si Nanowires Surface

Study on the Physico-Chemical Properties of the Si Nanowires Surface

The Role of the Molecular Hydrogen Formation in the Process of Metal-Ion Reduction on Multicrystalline Silicon in a Hydrofluoric Acid Matrix

Experimentally Derived Catalytic Etching Kinetics for Defect-Utilized Dual-Porous Silicon Formation

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