Dislocation-Guided Self-Running Droplets

Langmuir evaporation of stressed InSb and InAs (111)B crystals is studied using low-energy electron microscopy. The stress induces plastic relaxation by dislocation generation, whereas the evaporation results in self-running In droplets. The coexistence of in situ generated dislocations and self-running droplets allows droplet-dislocation interaction to be studied with minimal perturbation from other effects. The droplets run toward a preferred direction but are guided along dislocation lines before setting themself free once they accumulate mass and sufficient momentum to climb the energetic barrier posed by surface steps. The guiding effects are explained by surface stress which drives the mobile liquid along the dislocation line. This mechanism provides a means to control the direction of the self-running or self-propelled droplets, adding another degree of freedom to the growth and design of droplet-assisted micro- and nanostructures, for example, via interfacial dislocation network formed during heteroepitaxy.