Area-Selective Electroless Deposition of Gold Nanostructures on SiC Using Focused-Ion-Beam Preprocessing

Abstract

Area-selective electroless deposition of gold nanostructures on a 6H-SiC substrate is demonstrated. Gold nanostructures selectively grow on a focused ion beam (FIB)-irradiated area on the 6H-SiC substrate when the substrate is exposed to a pure HAuCl 4 aqueous solution. The nucleation of gold was more favorable on the Si face than on the C face. Quantitative evaluation of the amount of gold grown both on SiC and silicon is conducted to discuss the growth of gold, where silicon is a substrate we used in our previous study on this method. We reveal the mechanism of the growth of gold nanostructures as follows: Dangling bond defects formed in the FIB-irradiated area initiate the nucleation of gold by reducing Au ions in the solution at the surface. Once the SiC-gold or the silicon-gold boundary, which meets the Schottky contact condition, has formed, electrons in the non-FIB-irradiated region under/around the FIB-irradiated one also reduce Au ions on the gold surface through the boundary.

Growth of Nanogold at Interfaces between Locally Induced Naked Silicon Surfaces and Pure HAuCl4Solutions

“…This result demonstrates that the growth mechanism is different from the nucleation mechanism, and supports our proposed growth mechanism. 11 As previously reported, gold did not grow when a HAuCl 4 DMSO solution was used for the first exposure because a protic solvent is necessary for the gold nucleation and DMSO is an aprotic solvent. 10 The SEM results for gold nanostructures grown through the double exposure processes in Fig.…”

“…Our recent work suggested that the reduction of Au(III) ions by dangling bonds is the nucleation stage and that Au(III) ions are reduced in a different manner in the growth stage. 11 We suggested the following mechanism. Soon after silicon/gold interfaces form via gold nucleation, electrons in crystalline silicon near the interfaces reduce Au(III) ions in solution z E-mail: west@collon1.kuic.kyoto-u.ac.jp through the interfaces and the growing gold.…”

“…7,8 We previously reported an area-selective electroless method to deposit gold nanostructures on a silicon substrate from a pure HAuCl 4 aqueous solution, in absence of both HF and external reducing agents. [9][10][11] In our method, exposure to HAuCl 4 aqueous solution causes gold nanostructures to grow selectively on local silicon surfaces that have been irradiated with a FIB or a femtosecond laser. On the non-FIB-irradiated surface of the silicon substrate, the native oxide layer serves as a mask, preventing the growth of gold, and the layer is not corroded or damaged during the exposure because HF is not used.…”

Nanoscale Raman Imaging with Nanogold-Topped AFM Probes Fabricated by Area-Selective Electroless Deposition

“…Gold nanostructures grow on focused ion beam (FIB) irradiated local areas of silicon in response to exposure to a pure chloroauric acid (HAuCl 4 ) aqueous solution. [20][21][22][23] The mechanism of the growth of gold nanostructures which has been revealed so far is as follows. FIB irradiation removes native oxide layers of the a Present address: Inorganic Functional Materials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Shimoshidami, Moriyamaku, Nagoya, Aichi 463-8560, Japan.…”