Kinetics of congruent vaporization of ZnO islands.

We examine the congruent vaporization of ZnO islands using in situ transmission electron microscopy. Correlating quantitative measurements with a theoretical model offers a comprehensive understanding of the equilibrium conditions of the system, including equilibrium vapor pressure and surface free energy. Interestingly, the surface energy depends on temperature, presumably due to a charged surface at our specific condition of low P and high T. We find that the vaporization temperature decreases with decreasing system size, a trend that is more pronounced at higher T. Applying our results of island decay towards the growth of the ZnO provides new insights into the cooperative facet growth of anisotropic nanocrystals.