We propose three major research lines:
• Tailoring the electron mass and the transport properties – In a semiconductor the effective mass determines the inertia of the electron to an external stimulus. The finite value of the mobility ultimately limits the speed of integrated circuits and other devices. In most electronic circuits the electron flow is supposed to occur along a predetermined path, e.g. down the passageway connecting two transistors. However, typically only a small fraction of the available free carriers responds effectively to an external electric field. We want to show that based on the superlattice concept it may be possible to engineer the electron mass tensor in such a way that (i) all the available electronic states contribute to the electron flow. (ii) the intrinsic electron resistance to movement is greatly reduced. In addition, these ideas may enable to boost the electrical conductivity.
• Tailoring the nonlinearities in graphene and semiconductor superlattices and in electromagnetic metamaterials – Nonlinear electromagnetics (in particular nonlinear optics) has important applications in frequency multiplication or high-speed data transmission based on solitons. However, the nonlinear response of most natural materials is extremely weak. Previous studies have shown that by tailoring the electronic structure it is possible to enhance the nonlinear response. Here, we suggest boosting the nonlinear response by decreasing the intrinsic resistance of the electron to movement in engineered semiconductor or graphene superlattices. Our objective is to develop novel electronic materials with enhanced nonlinear response, and in addition to characterize the solitons supported both by these structures and by more conventional electromagnetic metamaterials based on metallic nanowire arrays.
• Effective medium theory – Effective medium theories are of key importance in the study of “low energy” physical phenomena since they enable reducing the inherent microscopic complexity of a physical system to a few effective parameters. Despite the fundamental differences between photons and electrons, there are many formal similarities between photonics and electronics, which ultimately result from the wave-particle duality. However, the theoretical frameworks typically adopted to describe wave propagation in electromagnetic media and in semiconductors are usually rather different. As a generalization of our previous studies in the context of electromagnetic metamaterials, we propose to develop a general effective medium framework based on the Hamiltonian formalism that enables describing “macroscopic excitations” in both electromagnetic metamaterials and semiconductor and graphene superlattices. Such common framework will enable establishing straightforward analogies between electronics and photonics.
|Start Date: 01-07-2013|
|End Date: 01-07-2015|
|Team: Mário Goncalo Mestre Verissimo Silveirinha, Tiago André Nogueira Morgado, David Emanuel Dias Fernandes, Sylvain Arnaud Lannebere|
|Groups: Antennas and Propagation – Co|
|Local Coordinator: Mário Goncalo Mestre Verissimo Silveirinha|