Adegoke et al- Real-Time TEM Observation of the Role of Defects on Nickel Silicide Propagation in Silicon Nanowires-ACS Nano 2024, 18, 14, 10270–10278

Temilade Esther Adegoke1,2, Raman Bekarevich3, Hugh Geaney1,2, Sergey Belochapkine1, Ursel Bangert1,4, and Kevin M. Ryan1,2,*

1Bernal Institute, University of Limerick, Limerick V94 T9PX, Ireland
2Department of Chemical Sciences, University of Limerick, Limerick V94 T9PX, Ireland
3Advanced Microscopy Laboratory, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin D02DA31, Ireland
4Department of Physics, University of Limerick, Limerick V94 T9PX, Ireland

Corresponding Author: Kevin M Ryan (
Received: January 23, 2024. Revised: March 13, 2024. Accepted: March 19, 2024. Published: March 21, 2024.
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Metal silicides have received significant attention due to their high process compatibility, low resistivity, and structural stability. In nanowire (NW) form, they have been widely prepared using metal diffusion into preformed Si NWs, enabling compositionally controlled high-quality metal silicide nanostructures. However, unlocking the full potential of metal silicide NWs for next-generation nanodevices requires an increased level of mechanistic understanding of this diffusion-driven transformation. Herein, using in situ transmission electron microscopy (TEM), we investigated the defect-controlled silicide formation dynamics in one-dimensional NWs. A solution-based synthetic route was developed to form Si NWs anchored to Ni NW stems as an optimal platform for in situ TEM studies of metal silicide formation. Multiple in situ annealing experiments led to Ni diffusion from the Ni NW stem into the Si NW, forming a nickel silicide. We observed the dynamics of Ni propagation in straight and kinked Si NWs, with some regions of the NWs acting as Ni sinks. In NWs with high defect distribution, we obtained direct evidence of nonuniform Ni diffusion and silicide retardation. The findings of this study provide insights into metal diffusion and silicide formation in complex NW structures, which are crucial from fundamental and application perspectives.

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