Electrochemical growth of gold on well-defined vicinal H–Si(111) surfaces studied by AFM and XRD

Munford, M. L.; Maroun, Fouad; Cortès, R.; Allongue, P.; Pasa, André A.

doi:10.1016/s0039-6028(03)00563-6

Cited by 64 publications

(73 citation statements)

References 44 publications

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“…Crystallographic tilting of heteroepitaxial systems with their vicinal substrates is often observed; 64 for instance, tilting of heteroepitaxial gold and silver on silicon has been described previously, 46,52,65Ϫ67 and has been ascribed to misfit dislocation (disregistry of the epilayer and substrate planes), 64,66,68 or misfit between the height of a gold monolayer and a silicon step. 67 In the case of a silicon surface in an aqueous HF solution under galvanic displacement conditions, the surface will certainly not be flat, and thus surface roughness is most likely playing an important role in the observed epitaxial tilting, leading to defects and dislocations.…”

Section: Resultsmentioning

confidence: 99%

Heteroepitaxial Growth of Gold Nanostructures on Silicon by Galvanic Displacement

et al. 2009

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This work focuses on the synthesis and interfacial characterization of gold nanostructures on silicon surfaces, including Si(111), Si(100), and Si nanowires. The synthetic approach uses galvanic displacement, a type of electroless deposition that takes place in an efficient manner under aqueous, room-temperature conditions. The case of gold-on-silicon has been widely studied and used for several applications and yet, a number of important, fundamental questions remain as to the nature of the interface. Some studies are suggestive of heteroepitaxial growth of gold on the silicon surface, whereas others point to the existence of a silicon؊gold intermetallic sandwiched between the metallic gold and the underlying silicon substrate. Through detailed high resolution transmission electron microscopy (TEM), combined with selected area electron diffraction (SAED) and nanobeam diffraction (NBD), heteroepitaxial gold that is grown by galvanic displacement is confirmed on both Si(100) and Si(111), as well as silicon nanowires. The coincident site lattice (CSL) of gold-on-silicon results in a very small 0.2% lattice mismatch due to the coincidence of four gold lattices to three of silicon. The presence of gold؊silicon intermetallics is suggested by the appearance of additional spots in the electron diffraction data. The gold؊silicon interfaces appear heterogeneous with distinct areas of heteroepitaxial gold on silicon, and others, less well-defined, where intermetallics may reside. The high resolution cross-sectional TEM images reveal a roughened silicon interface under these aqueous galvanic displacement conditions, which most likely promotes nucleation of metallic gold islands that merge over time: a Volmer؊Weber growth mechanism in the initial stages.

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Section: Resultsmentioning

confidence: 99%

Heteroepitaxial Growth of Gold Nanostructures on Silicon by Galvanic Displacement

et al. 2009

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“…The system acts as a galvanic cell, as has been shown previously for electroless etching of GaAs. 23 The importance of such galvanic effects in silicon etching has been pointed out by Allongue and coworkers; 24,25 they showed that cathodic protection of a polished ͑111͒ surface by a roughened back surface in oxygen-free NH 4 F solution helps to obtain ideally flat hydride-terminated ͑111͒ surfaces. Considering the discussion above one might expect the anisotropic etching characteristics ͑e.g., the anisotropic ratio͒ to depend on the particular ''facet geometry'' which, of course, should be timedependent.…”

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confidence: 99%

Anisotropic Etching of Three-Dimensional Shapes in Silicon

Kretschmer

Xia

Kelly

et al. 2004

J. Electrochem. Soc.

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As a result of the exposure to solution of different crystallographic facets during anisotropic etching of three-dimensional structures in silicon, the open-circuit potential of the semiconductor can change markedly. Using a ͑100͒Si substrate, masked to reveal ͑111͒ facets, we show that such a shift in potential can alter the chemical etch rates of the individual facets. The extent of the changes depends both on the facets exposed and on their relative areas. Because the surface geometry, and with it the silicon potential, change continuously in time, chemical etching must adapt continuously to these changes. This is an interesting example of a self-regulating system with a complex feedback mechanism. The effects described in this work clearly influence anisotropic etching ratios and are therefore important for the fabrication of microelectromechanical systems. Anisotropic etching of silicon in alkaline solutions is an important step in the technology of microelectromechanical systems ͑MEMS͒.1 Etching is employed to make high-definition, threedimensional structures in silicon wafers. These are required for a range of applications including miniature sensors for the measurement of pressure, flow, angular rate, and velocity. Other microsystems, such as filters, resonators, valves, pumps, and optomechanical connectors, can also be fabricated. The form that is obtained depends on the surface orientation of the wafer, the mask geometry, and the relative dissolution rates of the various crystallographic faces exposed during etching. The low etch rate of the ͑111͒ face with respect to that of other faces is exploited to produce deep grooves with flat walls, inverted pyramids, V-shaped grooves, and various other forms.1-3 For ͑100͒-oriented wafers, widely used in MEMS technology, the ratio of the etch rates of ͑111͒ and ͑100͒ faces, referred to here as the anisotropic ratio, is of vital importance for making high-resolution micromechanical structures. Although in the most favorable case the anisotropic ratio can exceed 100, 4 control and reproducibility at this level are poor. The composition of the etchant and the etching conditions as well as the ͑mis͒orientation of both the wafer surface and the mask edge are clearly important. Other factors which may play a role are dislocations in the silicon, defects at the silicon-mask interface, and impurities ͑even at very low concentrations͒ in the etchant.

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“…The HÀSi(111) surface was prepared by controlled chemical etching in 40 % NH 4 F + 50 mm (NH 4 ) 2 SO 3 to remove dissolved oxygen. [4] Figure 1 a shows a typical AFM image of the surface in which the steps are all 0.31 nm high and the Si(111) terraces are free of etch pits. After etching, the sample was quickly mounted on the holder of a rotating electrode with only the (111) polished face exposed to the solution (the sides of the sample were protected with an electrolytic scotch tape, Struers).…”

Section: Methodsmentioning

confidence: 99%

“…Among possible substrates, silicon is an excellent choice to grow metallic buffer layers because its surface can be prepared flat on the atomic scale in a reproducible way by wet chemical etching. [4] In addition, silicon is compatible with all microfabrication techniques and the rectifying electric properties of the metal/silicon interface may be of high interest in some applications.…”

Section: Introductionmentioning

confidence: 99%

“…From an electrochemical viewpoint, this 3D metal growth can be assigned to a faster electrochemical transfer on the early-formed nuclei. [15,16] In two preliminary studies, it was reported that gold electrodeposition on H-Si(111) may lead to 3D films [13,17] or to very smooth layers [18] by a proper choice of the plating solution and of the electrochemical conditions. Clearly, the surface energy is not the sole parameter which governs the growth modes.…”

Section: Introductionmentioning

confidence: 99%

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Epitaxial Growth of Gold on HSi(111): The Determining Role of Hydrogen Evolution

Prod’homme¹,

Warren²,

Cortès³

et al. 2010

ChemPhysChem

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The potential dependence of gold electrodeposition on H-terminated Si(111) is studied in acidic electrolyte by means of atomic force microscopy and X-ray diffraction. The Au films (≤66 monolayers (ML)≈16 nm) are found to be (111)-oriented and in strong epitaxy with the Si(111) surface lattice, with two in-plane orientations separated by 180°. The deposit morphology is controlled by the deposition potential and can be islandlike or atomically flat. The flat morphology is accompanied by a preferential growth of 180°-rotated Au planes with respect to the Si bulk lattice which takes place at potentials where the hydrogen evolution reaction occurs. Obtaining ultraflat Au layers on Si(111) contrasts with the commonly observed islandlike morphology of electrodeposited films on semiconductors. This behavior is discussed in terms of a nucleation coupled with hydrogen evolution reaction (HER) and an enhanced Au adatom mobility induced by this reaction.

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Electrochemical growth of gold on well-defined vicinal H–Si(111) surfaces studied by AFM and XRD

Cited by 64 publications

References 44 publications

Heteroepitaxial Growth of Gold Nanostructures on Silicon by Galvanic Displacement

Heteroepitaxial Growth of Gold Nanostructures on Silicon by Galvanic Displacement

Anisotropic Etching of Three-Dimensional Shapes in Silicon

Epitaxial Growth of Gold on HSi(111): The Determining Role of Hydrogen Evolution

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