Research objectives and content
It is well documented that the possibility of stabilising excitons at room temperature in semiconductor heterostructures is a key factor for high performance optoelectronic devices. This should be realised via the suppression of the exciton-phonon scattering. It is the main part of this research project to study the basic properties of the exciton-phonon coupling in low dimensional structures. The proposal takes advantage of the unique physical properties of ZnS, where the 3D exciton binding energy is close to that of the LO phonon, and so, in quantum wells structures, excitations of the free exciton can be tuned to smaller, larger or resonant with the LO phonon energy. The non-local and local exciton-phonon complexes as well as the exciton-phonon scattering will be investigated by mean of absorption, photoluminescence excitation, two-photon and magneto-optical spectroscopies. In particular, the application of an electric field in a Schottky structure will allow the exciton binding energy to be tuned through the LO phonon energy via the quantum confined Stark effect. The results will be used to explore phonon scattering suppression in a demonstrator structure.
Training content (objective, benefit and expected impact)
The proposed project will allow the applicant to undergo training in the use of new spectroscopy techniques (magneto-optical and two photon absorption). Previous work (see curriculum vitae) has allowed me to investigate the electron-phonon coupling when a carrier is bound to a doping impurity. The extension to the study of the exciton-phonon complex, which has additional internal degrees of freedom will give me a better knowledge of the properties these kind of quasiparticles. Furthermore, this is a novel basic physics proposal which will provide the applicant with the means to explore new optoelectronic devices and to contribute to the development of high gain UV lasers for industrial use.
Links with industry / industrial relevance (22)