Production method of gold single crystal with high quality and large grain size and its application to a SPM substrate

Yoshimatsu, Nobuki; Kawasaki, Takehiko; Ban, Kanako; Kusaka, Takao; Ikeda, T.

doi:10.1380/ejssnt.2005.524

Cited by 5 publications

(5 citation statements)

References 2 publications

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“…The use of iodine/potassium iodide solutions as gold etchants is well-established − and has even been implemented in nanoscale systems. , However, it is unlikely that the iodide impurities present in the CTAB are etching the gold surfaces during nanorod formation, because well-dispersed spherical nanocrystals are still produced in the reaction, indicating that the CTAB capping ligand layer has not been disrupted or the seeds etched to molecular byproducts. However, this etchant model may apply to the iodide-induced aggregation of nanorods postsynthesis.…”

Section: Resultsmentioning

confidence: 99%

Iodide in CTAB Prevents Gold Nanorod Formation

2009

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The gold nanocrystal seed-mediated approach using cetyltrimethylammonium bromide (CTAB) as a stabilizing surfactant is commonly used to make large quantities of monodisperse gold nanorods. This method, however, has been at times difficult to reproduce in different laboratories. We recently showed [Smith, D. K.; Korgel, B. A. Langmuir 2008, 24, 644-649] that a very low concentration impurity in CTAB obtained from some suppliers prevents nanorod growth but were not able to identify the impurity. Here, we report that the impurity is iodide. Inductively coupled plasma mass spectroscopy (ICP-MS) revealed that iodide concentrations vary in CTAB from different suppliers, from less than 2.75 ppm up to 840 ppm. When CTAB with iodide concentrations greater than 50 ppm is used, nanorods do not form and the product consists entirely of spherical nanocrystals. Iodide slows the reduction of Au(III) to Au0. Iodide adsorption on Au {111} surfaces inhibits nanorod growth.

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Section: Resultsmentioning

confidence: 99%

Iodide in CTAB Prevents Gold Nanorod Formation

2009

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“…3b). 23 The final reaction occurs between the remaining triiodide and iodide (I À ) when L(+)-ascorbic acid is incorporated into the solution (photograph in Fig. 3c).…”

Section: Self-termination Of the Egp Processmentioning

confidence: 99%

Robust nanogap electrodes by self-terminating electroless gold plating

et al. 2012

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Robust nanogap electrodes for nanodevices with a separation of 3.0 ± 1.7 nm were simultaneously mass-produced at a yield of 90% by a combination of electron beam lithography (EBL) and electroless gold plating (EGP). Nanogap electrodes demonstrated their robustness as they maintained their structure unchanged up to temperatures of 170 °C, during the isotropic oxygen plasma ashing removal of the amorphous carbon overlayer resulting from scanning electron microscopy observations, therefore maintaining their surface reactivity for EGP and formation of a self-assembled monolayer. A gold layer grows over the electrode surface during EGP, narrowing the separation between the electrodes; growth stops around 3 nm due to a self-termination phenomenon. This is the main factor in the high yield and reproducibility of the EGP process because it prevents contact between the electrodes. A 90% yield is achieved by also controlling the etching and physisorption of gold clusters, which is accomplished by reduction of triiodide ions and heat treatment of the EGP solution, respectively. A mixed self-assembled monolayer of octanethiol and decanedithiol can be formed at the surface of the nanogap electrodes after the oxygen plasma treatment, and decanethiol-protected Au nanoparticles were chemisorbed between the self-terminated nanogap electrodes via decanedithiol. Chemically assembled single-electron transistors based on the nanogap electrodes exhibit ideal, stable, and reproducible Coulomb diamonds.

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“…To date many gold nanoparticle shapes have been identified. Spheres,13 triangular and hexagonal plates,4, 14–20 wires,19 and branched species,2 to name the most important, have been discussed in the literature. The physical properties, in particular the optical properties, of such nanoparticles strongly depend on their shape, size, and morphology.…”

Section: Proposed Band Assignment For Ters and Sers Spectra Of Cystinmentioning

confidence: 99%