| Summary: | 碩士 === 國立交通大學 === 電子物理系所 === 106 === In our study, we use Ni as a catalyzing material to grow Si nanowires on Si substrate in ultra-high vacuum chemical vapor deposition (UHV-CVD) system. Comparing with electron beam evaporation (EBE) system, we investigate the morphology and growth directions of Si nanowires as well as epitaxial relationships between catalyst and Si nanowires grown from vapor-solid-solid (VSS) mechanism. Furthermore, we synthesis the Si/GaN heterostructure nanowires by connecting UHV-CVD with hydride vapor phase epitaxy (HVPE) system, analyzing the geometric and morphological characteristics of this heterostructure nanowires.
We find that the annealing temperature for Ni-Si alloy, which is NiSi2, significantly has an influence on wire morphology and rate limiting steps. Single-crystalline SiNWs are grown exhibiting the solid-state catalyst tip with defect-free interfaces. From SEM and HRTEM images, we observe that the growth directions of Si nanowires are mainly along <110> and <112>, while the Si nanowires are bounded by well-defined facets of low-index crystalline planes in order to minimize the surface energy. We also obtain statistic data to realize the growth directions in our VSS experiment and compare with other growth mechanisms like VLS and OAG method. For Si/GaN nanowire heterostructures, we present the epitaxial relationships at the heterointerface and discuss the growth mechanisms, which may be useful in the design of branching nanowire heteroctructures for advanced applications.
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