Kris's Research Notes

September 4, 2012

VLS Nanowire Simulations — Exchange barrier

Filed under: KMC, Nanowire — Kris Reyes @ 6:10 pm

In this note, we continue to study the effect of energy parameters have on the growth modes observed in VLS nanowire growth. Here we consider the energy \epsilon, the additive barrier for exchanges at solid/liquid interface. This governs the attachment and detachment kinetics of solid material to and from the interface, and hence roughly measures the mobility of the interface.

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August 27, 2012

VLS Nanowire Simulations – C Bonds

Filed under: KMC, Nanowire — Kris Reyes @ 5:30 pm

In this note, we continue to study the effect of energy parameters on VLS nanowire growth. Here we examine the role of the \gamma(B,C) and \gamma(C,C) bonds, the liquid-solid and solid-solid bond strengths, respectively.

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August 24, 2012

VLC Nanowire Simulations — B Bonds

Filed under: KMC, Nanowire — Kris Reyes @ 4:40 pm

This note is a follow-up to our previous one, and continues to explore the effect of the energy parameters in the resulting structure after attempting to grow nanowires by VLS method. In this note, we vary the bonds \gamma(B, B) and \gamma(B, C) — i.e. the strength between liquid-liquid and liquid-solid bonds.

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August 23, 2012

Reaction Events

Filed under: KMC, Nanowire — Kris Reyes @ 9:53 pm

In this note, we describe a new reaction event which is incorporated in our model in order to correctly simulate VLS nanowire growth.

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June 15, 2012

3D Nanowires — Liquid Droplets

Filed under: Nanowire — Kris Reyes @ 12:31 pm

In 2+1 dimensions, KMC simulations tend to facet easily. This makes sense as more bonds nearest and next-nearest neighbor bonds occur in 2+1 dimensions. Indeed, on the diamond lattice used throughout our 3D simulations, an atom posses 4 nearest neighbor and 12 next-nearest neighbor bonds. If we wish to model nanowire growth by the VLS method, it is desirable for our liquid (which resides on the lattice) to not be faceted. In this note, we describe preliminary results in our search for the correct energy and temperature parameters that allow this to occur.

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September 15, 2011

Nanowires, Part 4: Mixing

Filed under: Nanowire — Kris Reyes @ 6:16 am

Recall in the previous post, we observed a significant amount of mixing of the solid phase as the nanowire grew. This mixing is mostly a result of liquid B atoms diffusing through the A material quickly. This is probably not physical and hence we wish to control the amount of atom-atom exchanges within the solid. In this note, we describe how to do this and its effect on the growth of the nanowire. We also study how deposition rate and droplet size changes the growth mode.

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September 8, 2011

Nanowires, part 3

Filed under: Nanowire — Kris Reyes @ 6:56 pm

In this note, we describe the role of energy parameters in our model of nanowire growth. We give conditions on the energies to encourage growth (rather than etching) and explain how energies determine how fast atom diffuses through the liquid droplet onto the interface. Simulations are done on a hexagonal lattice.

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