Tokyo Tech News

Nanogap electrodes: Self-terminating electroless gold plating for electronic nanodevices


February 28, 2013

Nanogap electrodes are a platform for single nanoscale electronic devices such as single-electron transistors (SETs) and molecular devices. They enable the harnessing of the electrical characteristics of many kinds of nanostructures such as nanoparticles and functional molecules by interconnecting these nanostructures with two terminals, thus for example, integrating nanometer-sized molecules into macroscopic electronic circuits. 

However, it is difficult to fabricate integrated nanogap electrodes with sufficient robustness to obtain chemical reactivity for bottom-up processes even after obtaining scanning electron microscopy (SEM) images. 

Now, Yutaka Majima and colleagues at Tokyo Institute of Technology have demonstrated the fabrication process of robust nanogap electrodes with a separation of 3.0 ± 1.7 nm at a yield of 90 % by a process combining electron beam lithography and electroless gold plating (EGP). 

A gold layer is grown over the electrode surface during EGP, thereby narrowing the separation between the electrodes, and the growth stops at 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. 

The electroless plated nanogap electrodes are an important component for the development of practically important electronic nanodevices such as SETs and molecular devices, which are chemically assembled within a solution.

Authors: Victor M. Serdio V., Yasuo Azuma, Shuhei Takeshita, Taro Muraki, Toshiharu Teranishi, and Yutaka Majima
Title of original paper: Robust Nanogap Electrodes by Self-terminating Electroless Gold Plating
Journal, volume, pages and year: Nan2013.06.24 リニューアルに伴う移行oscale 4, 7161, 2012. Digital Object Identifier (DOI): 10.1039/c2nr32232c
Affiliations: Materials and Structures Laboratory
Department website:



Electroless gold plated (EGP) nanogap electrodes.