Browsing by Author "Lin, Yung-Chen"

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Kinetic Competition Model and Size-Dependent Phase Selection in 1-D Nanostructures
(2012-06-01)
Chen, Yu
;
Lin, Yung-Chen
;
Huang, Chun-Wei
;
Wang, Chun-Wen
;
Chen, Lih-Juann
The first phase selection and the phase formation sequence between metal and silicon (Si) couples are indispensably significant to microelectronics. With increasing scaling of device dimension to nano regime, established thermodynamic and kinetic models in bulk and thin film fail to apply in 1-D nanostructures. Herein, we present an unique size-dependent first phase formation sequence in 1-D nanostructures, with Ni-Si as the model system. Interfacial-limited phase which forms the last in thin film, NiSi2, appears as the dominant first phase at 300-800 degrees C due to the elimination of continuous grain boundaries in 1-D suicides. On the other hand, theta-Ni2Si, the most competitive diffusion-limited phase takes over NiSi2 and wins out as the first phase in small diameter nanowires at 800 degrees C. Kinetic parameters extracted from in situ transmission electron microscope studies and a modified kinetic growth competition model quantitatively explain this observation. An estimated critical diameter from the model agrees reasonably well with observations.
The Influence of Surface Oxide on the Growth of Metal/Semiconductor Nanowires
(2011-07-01)
Lu, Kuo-Chang
;
Wu, Wen-Wei
;
Ouyang, Hao
;
Lin, Yung-Chen
;
Huang, Yu
We report the critical effects of oxide on the growth of nanostructures through silicide formation. Under an in situ ultrahigh vacuum transmission electron microscope, it is observed from the conversion of Si nanowires into the metallic PtSi grains epitaxially through controlled reactions between lithographically defined Pt pads and Si nanowires. With oxide, instead of contact area, single crystal PtSi grains start forming either near the center between two adjacent pads or from the ends of Si nanowires, resulting in the heterostructure formation of Si/PtSi/Si. Without oxide, transformation from Si into PtSi begins at the contact area between them, resulting in the heterostructure formation of PtSi/Si/PtSi. The nanowire heterostructures have an atomically sharp interface with epitaxial relationships of Si(20-2)//PtSi(10-1) and Si[111]//PtSi[111]. Additionally, it has been observed that; the existence of oxide significantly affects not only the growth position but also the growth behavior and the growth rate by two orders of magnitude. Molecular dynamics simulations have been performed to support our experimental results and the proposed growth mechanisms. In addition to fundamental science, the significance of the study matters for future processing techniques in nanotechnology and related applications as well.