Electronic Structure of NiSi₂/Si Interface Interrupted by a One-atomic Au Layer

Chia-Yi Wu^1*, Jia-An Lin¹, Yi-Chia Chou²

¹Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
²Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan

* Presenter:Chia-Yi Wu, email:cywu.c@nycu.edu.tw

Silicides are reliable materials to reduce the contact resistance of silicon-based devices in complementary metal oxide semiconductor (CMOS) technology. The interface characterization of silicide and silicon has been a popular topic, because the interface properties may impact on contact resistivity. Silicide-embedded nanowires by the vapor-liquid-solid (VLS) method had been shown in the previous research¹. It is an interesting nanostructure and might have the potential for semiconductor devices, but its properties and details have not been understood thoroughly. In this work, we used atomic-scale scanning transmission electron microscopy (STEM) to observe the interface structure. We found that a one-atomic thick gold layer existed at the interface between nickel silicide nanocrystal and silicon in the silicon nanowires. The existence of the gold layer had been further supported by energy-dispersive X-ray spectroscopy (EDS) and QSTEM simulations. Moreover, we used energy electron loss spectroscopy (EELS) to characterize the electronic structure in the NiSi₂/Si interface with interrupting by the gold layer. Combine with simulated results, we found that the interrupting by the gold layer might cause the stronger coupling of Ni and Si atoms.

Reference
1. Panciera, F. et al. Synthesis of nanostructures in nanowires using sequential catalyst reactions. Nature Materials 14, 820-825, doi:10.1038/nmat4352 (2015).

Keywords: silicide/Si interface, nanostructure, electronic structure