Study opens possibility for controlling nanowire properties and integrating nanowires into real devices

 

Collaborative research between GIST and IBM Watson Research Center published in Nano Letters

 

 

A Korean research team has uncovered the kinetic properties of the nanosize Au catalyst, which determine the growth properties of nanowires, using in-situ transmission electron microscopy (TEM). Nanowires are ultrafine wires used in silicon semiconductor processes and electronic device fabrication, and as such, the study is expected to help resolve the problems surrounding electronic devices such as transistors and energy devices such as solar cells, which are currently faced with limitations in terms of integration, functionality, and efficiency.

 

The research was led by corresponding author Prof. Bong-Joong Kim of GIST School of Materials Science and Engineering, in collaboration with IBM Watson Research Center of the United States, and was supported by the Global Research Network program of the National Research Foundation of Korea and by the Next Generation Solar Cell Development program of GIST Research Institute for Solar and Sustainable Energies. The result was published in the August 2014 issue of Nano Letters, a highly prestigious research journal in nanoscience and nanotechnology. (Title: Au Transport in Catalyst Coarsening and Si Nanowire Formation)

 

Semiconductor nanowires are typically grown using nano-catalysts. However, it is difficult to understand and control their growth properties (growth direction, length, width, density, surface morphology, etc.), which in turn makes it difficult to integrate them into real nano-devices. Up to now, post-mortem examination has been carried out after growing nanowires.

 

Prof. Kim’s group monitored, in real time, the dynamics of catalyst coarsening that occurs at the very beginning of nanowire growth, and then quantitatively measured the kinetics combined with a simple analytical model. This opens the possibility to repeatedly integrate the wires with various materials into nano-devices.

 

The research team compared the three ambient gas environments of disilane, oxygen, and vacuum. For each experiment, they introduced each gas into a closed area in pole-piece region in a transmission electron microscope while observing the entire process of the coarsening event of the Au catalyst at a fast acquisition rate of imaging (30 frames/sec).

 

The team measured the size of the Au nano-catalyst placed on the two substrates in different atomic orientations and with varying temperature and gas environment as time progressed, and they found that the catalyst volume changes linearly with time, and the rate constant increases with oxygen, vacuum, and disilane, in that order.

 

Prof. Kim said, “The research suggested the mechanism and kinetics of the Au nano-catalyst coarsening that occurs during the process of nanowire evolution, with the assistance of a generalized quantitative modeling.” “In the near future, the knowledge from this research is expected to dramatically increase the potential of controlling the growth properties of nanowires with changing some simple parameters, and of implementing real nano-device applications,” he added.

 

For further information or inquiries, please contact isso@gist.ac.kr.