Browsing by Author "Reuter, M. C."

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Atomic-Scale Variability and Control of III-V Nanowire Growth Kinetics
(2014-01-17)
Chou, Y. -C.
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Hillerich, K.
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Tersoff, J.
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Reuter, M. C.
;
Dick, K. A.
In the growth of nanoscale device structures, the ultimate goal is atomic-level precision. By growing III-V nanowires in a transmission electron microscope, we measured the local kinetics in situ as each atomic plane was added at the catalyst-nanowire growth interface by the vapor-liquid-solid process. During growth of gallium phosphide nanowires at typical V/III ratios, we found surprising fluctuations in growth rate, even under steady growth conditions. We correlated these fluctuations with the formation of twin defects in the nanowire, and found that these variations can be suppressed by switching to growth conditions with a low V/III ratio. We derive a growth model showing that this unexpected variation in local growth kinetics reflects the very different supply pathways of the V and III species. The model explains under which conditions the growth rate can be controlled precisely at the atomic level.
In Situ Growth of Si Nanowires Using Transmission Electron Microscopy
(2013-01-01)
Chou, Y. -C.
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Wen, C. -Y.
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Reuter, M. C.
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Su, D.
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Stach, E. A.
We discuss the use of the alloy catalyst AgAu to grow silicon nanowires and Si/Ge heterojunctions. Nanoscale particles of the catalyst with compositions Ag:Au varying from 2:1 to 1:2 can be fabricated and used to form Si nanowires with high crystal quality, and SiGe interfaces that are close to atomically abrupt. In situ experiments in the TEM are essential for investigating the mechanisms of growth with these alloy catalysts. We describe the relationship between growth kinetics and catalyst state, as well as the environmental stability of the alloy catalysts.
Synthesis of nanostructures in nanowires using sequential catalyst reactions
(2015-08-01)
Panciera, F.
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Chou, Y. -C.
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Reuter, M. C.
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Zakharov, D.
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Stach, E. A.
Nanowire growth by the vapour-liquid-solid (VLS) process enables a high level of control over nanowire composition, diameter, growth direction, branching and kinking, periodic twinning, and crystal structure. The tremendous impact of VLS-grown nanowires is due to this structural versatility, generating applications ranging from solid-state lighting and single-photon sources to thermoelectric devices. Here, we show that the morphology of these nanostructures can be further tailored by using the liquid droplets that catalyse nanowire growth as a \'mixing bowl\', in which growth materials are sequentially supplied to nucleate new phases. Growing within the liquid, these phases adopt the shape of faceted nanocrystals that are then incorporated into the nanowires by further growth. We demonstrate this concept by epitaxially incorporating metal silicide nanocrystals into Si nanowires with defect-free interfaces, and discuss how this process can be generalized to create complex nanowire-based heterostructures.