High-frequency response of two-well nanostructures

A consistent analytical theory is developed for coherent resonant electron tunnelling in a two-well nanostructure in the presence of a weak electromagnetic field. Simple expressions derived for the transmission coefficient and linear response of the two-well nanostructure make it possible to clarify the physics of processes and to express the gain as a function of the structure parameters. It is shown that the high-frequency response of the two-well nanostructure considerably exceeds the response of a one-well structure (resonance-tunnel diode) and that the application of a constant electric field makes it possible to tune the oscillation frequency and to increase the gain. It is concluded that two-well nanostructures can be used in designing terahertz oscillators. It is shown that, in contrast to a resonance-tunnel diode, interference of electrons between the wells and radiative laser-type transition play a decisive role in such structures. (C) 2005 Pleiades Publishing, Inc.