Kris's Research Notes

April 26, 2012

Mullins Sekerka Instability and Liquid Cores

Filed under: GaAs Simulations — Kris Reyes @ 10:55 pm

In this note, we model the formation of liquid cores during droplet crystallization as a Mullins Sekerka instability. We then compare the theoretical critical curve for the instability with simulation results.



A Mullins-Sekerka Instability for Crystallization

Filed under: GaAs Simulations — Kris Reyes @ 9:05 am

In this note, we show how the deposition of As into liquid Ga exhibits a Mullins-Sekerka instability.


April 24, 2012

Morphological Phase Diagrams

Filed under: GaAs Simulations — Kris Reyes @ 9:02 am

In this note, we present three morphological phase diagrams illustrating the presence of (1) nanorings, (2) liquid cores and (3) nucleation. The experimental procedure is altered to omit the last annealing step, in order to simplify the discussion. We also consider higher temperatures and lower As flux than before.


April 10, 2012

Nucleation Regime. Part 2

Filed under: GaAs Simulations — Kris Reyes @ 11:41 pm

This note is a follow-up to this post. In that note, we developed an expression for when nucleation is possible by expressing the rate of change in concentration c_r as the net effect of atoms impinging upon the nucleus (given by an As flux and Laplace’s equation) and atoms leaving the nucleus (given by the Gibbs-Thomson relation). In this note, we discuss the problems with the discussion in that post and describe alternative models for surface nucleation.