Biomedical Engineering Reference
In-Depth Information
Chapter 8
Quantum Interference Effects on the Electronic
Transmission Through Quantum Dot Molecules
Rodolfo H. Romero, Daniel A. Lovey, Diego Sebastian Acosta Coden,
and Sergio S. Gomez
Abstract
The fabrication and control of devices at nanometric scale emphasizes
the importance of quantum effects on the electronic motion in semiconductor
heterostructures. The size of the systems through which the electrons move makes
mandatory to take into account their wave-like character. As a consequence, the typ-
ical interference effects play an important role. In this chapter the noticeable Fano
and Aharonov-Bohm effects in the transmission through a ring of quantum dots
threaded by a magnetic flux will be discussed. They arise from the interference of
the electron wave function when propagating along several transmission paths. The
effects manifest themselves as peaks of high conductance and dips of cancellations
of transmission along the ring. The control of the gate potentials applied to quantum
dots and the magnetic field threading the ring allow one to tune the energies at which
high and low transmissions occur.
8.1
Introduction
The persistent search for miniaturization of electronic devices has led to the
development of new physical systems where the charge carriers are tightly confined.
In semiconductor heterostructures, the electronic motion can be confined close to
its interface, forming a two-dimensional electron gas (2DEG). Further confinement
in the lateral dimensions can be achieved by applying bias voltages to metallic
gates patterned in-plane or on-top of the interface. In this way, nanometric island of
electron charges—quantum dots (QDs)—can be produced and precisely controlled.
The discretization of their energy levels, due to the spatial restriction of the
R.H. Romero (
) D.A. Lovey D.S. Acosta Coden S.S. Gomez
Facultad de Ciencias Exactas y Naturales y Agrimensura, and Instituto de Modelado e Innovacion
Tecnol ogica (CONICET-UNNE) Av. Libertad 5500 (3400) Corrientes, Argentina
