Figure shows the InAs thickness vs. time as predicted by Eq. 4 (solid line), assuming InAs growth to occur only at the In interface. The InAs thickness limited by the reaction rate is also shown as reference (dashed line). By comparing the two curves, it is clear that diffusion slows down the growth rate significantly already for InAs thicknesses as small as ~ 10 nm. Given the thickness of the InAs nano-islands in our samples, we suspect that growth is limited by self-diffusion and/or by the electrochemical deposition rate.