Near-surface transport of semiconductor nanoclusters upon cyclic photoexcitation

A mechanism for the directed motion of a semiconductor nanocluster along a polar substrate upon cyclic photoexcitation that alters the electron density distribution inside the particle is studied. A model that allows us to estimate the average velocity and optimize the system parameters (particle size, distance between the particle and the substrate, the average cycle duration, and charge distribution in the substrate) so as to ensure the maximum velocity is proposed. At the optimum parameters, the average velocity of directed motion can be quite high (~3 mm/s).