Regardless of which interface is contributing the most to the InAs growth, it is clear from Eq. 4 that for small InAs thicknesses (x), growth is limited by the reaction rate constant, 𝑘𝑘 𝑅𝑅 . On the other hand, after a certain thickness the diffusion rate � 𝑘𝑘 𝐷𝐷 𝑥𝑥 � will determine the overall growth.