Kris's Research Notes

September 15, 2011

GaAs Simulations: Droplet growth and Crystallization at High Temperatures

Filed under: GaAs Simulations — Kris Reyes @ 7:17 pm

In this note, we present more simulation results of Ga liquid droplet growth and subsequent crystallization at various temperatures, including T = 623K. In experiments, well-defined “doughnuts” form. Our simulations agree with this.



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.


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.


September 6, 2011

Nanowires, Part 2

Filed under: GaAs Simulations — Kris Reyes @ 1:05 pm

Recall in this previous post, we discussed our first steps toward simulating VLS nanowire growth. In those simulations, we observed that the ‘solid’ behaved like a liquid which wet the substrate. Here, we address this by adjusting the desorption rate so that the solid phase is in equilibrium with the vapor phase.


Droplet Formation and Crystallization

Filed under: GaAs Simulations — Kris Reyes @ 11:51 am

We simulate droplet formation and crystallization at various energy parameters and temperatures.