Chapter 11 - Tunneling time in nanostructures

Abstract

This chapter reviews the theoretical approaches for tunneling times to illustrate the problems involving nanostructures. There is not yet a proper treatment of tunneling times in very small nanostructures with single, localized electrons, where the radius of "localization" is on the same order of magnitude as the length of the barrier L. On the other hand, materials research and rapid systems development with nanostructures, particularly for microelectronic purposes, clamor for an understanding of time constants or operation times and the tunneling times involved. Larmor clock approach has been studied to tunneling time, based on measuring the spin rotation of an electron under a weak magnetic field acting on the region of interest. A Green's function formalism is developed for the traversal and reflection times and the rest of the existing major approaches to the time problem is reviewed. It seems that the race between "physical" and "chemical" nanostructured materials is running decidedly in favor of chemistry: At present, the physical requirements for further investigation of nanostructured tunneling devices can be satisfied by chemically size-tailoring zero-, one-, two-, or higher dimensional cluster materials in molecular scale, although fabrication techniques for hybrid or pure cluster nanodevices are still lacking.