seminars

Inter-atomic coulombic decay in quantum wells

Physical and Analytical Chemistry Seminar

Lecturer: Tamar Goldzak

Date:
05 Jun 2016 @ 12:30

Location: Faculty Seminar Room

Interatomic/intermolecular Coulombic decay (ICD) is a very efficient and fast electron
relaxation process relying on the correlation between electrons. Such process occurs by passing
the excess excitation energy of one electron to another electron in a neighboring atom or
molecule, resulting in the subsequent ionization of this atom/molecule. Past studies of ICD
focused on atom and molecular clusters. It has been proven to be very efficient even in
extremely long interatomic/intermolecular distances. The ICD was observed experimentally in
noble-gas, clusters and dimers. We study the ICD process in a two coupled quantum wells
(QWs) nano-structure. The ICD in the QWs nano-structure works in the same manner as in
molecular clusters. QWs are widely used in optoelectronic devices such as laser diodes and
photodetectors. Excited electrons in QWs have many relaxation pathways, such as spontaneous
photon emission and interaction with phonons. These processes are competing with the ICD in
our system. We study the ICD decay process, using the Hermitian and non-Hermitian formalism
of quantum mechanics, and compared it with the other decay processes in our system.
In our work we engineered our system such that the ICD is enhanced, and overcome other
decay mechanism in the QWs nano-structure. Furthermore, we design the nano-structure such
that the ICD electron is ionized in the perpendicular direction to the semiconductor layers. This
means that only vertical current are expected in such a case, even when the bias on the nanostructure
is small as one wishes.
Based on our results we design an experiment that will observe the ICD phenomenon in QWs
nano-structure. Moreover, based on our finding a wavelength-sensitive detector which is
efficient even at low intensities can be designed. In this work we collaborated with the group of
Prof. Gad Bahir from the electrical engineering faculty at the Technion.