We propose a simple design of a rotary nanomotor comprised of three quantum dots attached to the rotating ring (rotor) in the presence of an in-plane dc electric field. The quantum dots (sites) can be coupled to or decoupled from source and drain carrier reservoirs, depending on the relative positions of the leads and the dots. We derive equations for the site populations and solve these equations numerically jointly with the Langevin-type equation for the rotational angle. It is shown that the synchronous loading and unloading of the sites results in unidirectional rotation of the nanomotor. The corresponding particle current, torque, and energy conversion efficiency are determined. Our studies are applicable both to biologically-inspired rotary nanomotors, the F 0 motor of ATP synthase and the bacterial flagellar motor, which use protons as carriers, and to novel artificial semiconductor systems using electrons. The efficiency of this semiconductor analog of the rotary biomotors is up to 85% at room temperature.

We examine 10 nm thick film structures containing either Hf or Ti sandwiched between two respective oxide layers. The layers are deposited onto heated substrates to create a diffusion region. We observe a high degree of light sensitivity of the electric current through the film thickness for one polarity of an applied voltage. For the other polarity, the current is not affected by the light. We explain the observed phenomenology using the singleparticle model based on the existence of interface states on the metal-oxide interfaces.

No abstract