Forming Silicides and Germanides in Vertical Semiconductor Nanowires
Yi-Chia Chou1*
1Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
* Presenter:Yi-Chia Chou,
Many electronic devices, such as field-effect transistors, depend on achieving precise control of both the composition and atomic arrangement within a semiconductor nanostructure and the contact of the nanostructure with the larger-scale circuit. Control of structure and contacts involves integrating different types of materials and bridging between length scales. Here we show how complex nanostructures can be formed that include silicide and germanide nanocrystals embedded within Si and Ge nanowires. We form the silicide or germanide by adding the appropriate metal to the liquid droplets of VLS grown nanowires. Solid silicide or germanide nanocrystals form in the liquid and have freedom to move and rotate until a low-energy interface with the nanowire is found. After contact is made, certain types of silicide and germanide nanocrystals remain attached to the nanowire while others break away without forming a permanent contact. Only the nanocrystals that remain attached to the nanowire can then be incorporated by continued growth of the nanowire. We have examined the factors that determine crystal adhesion to the nanowire and suggest that it depends on the symmetry of the contact interface and hence the crystal structures of the materials. To expand the range of possible materials, we introduce the use of phase transformations within the nanocrystal. The variety of nanostructures with incorporated nanocrystals that it is possible to make using such reaction schemes potentially raises the chances for designing particular electronic and contact properties for nanostructured device applications.

Keywords: Nanowire, phase transformation, silicide, germanide