I am a materials physicist with broad interests and expertise in solid-state physics and nanoscience and technology. Currently, my main areas of research aim at expanding the functionalities of modern semiconducting devices to empower different applications in the areas of optoelectronic, energy-related, and sensing devices. Seeking to go beyond silicon, I continue to work on Si-based nanomaterials, especially SiGe structures grown by molecular beam epitaxy (MBE), and also organic and hybrid semiconductors. I develop and regularly use methods of optical spectroscopy to study optical, electronic and vibrational properties, mainly spectroscopic ellipsometry, Raman scattering, and photoluminescence.
November 1989 – January 1990. postdoctoral research associate at Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
February 1990 – July 1992. research contract at Centro Nacional de Microelectrónica, CSIC, Madrid, Spain.
October 1992 – April 1996. research contract at the Institut de Ciència de Materials, CSIC, Barcelona, Spain.
between 1992-1994. several research stays at the Paul-Drude Institut für Festkörperelektronik, Berlin, Germany.
since May 1996. staff researcher at the Institut de Ciència de Materials, CSIC, Barcelona.
since October 2006. head of department “Nanostructured Materials”.
More specifically, in my recent research I am working in the fabrication and characterization of semiconductor nanostructures for photovoltaic (PV) and thermoelectric (TE) applications, in the latter case with the explicit purpose of exploiting the reduced dimensionality to enhance TE power. The SiGe nanostructures fabricated using MBE are compatible with all-Si technology, thus enabling monolithic integration with established Si processing, for example as on-chip coolers. Their study is also expected to lead to deep insights about the currently rather limited understanding of the flow heat control and the effect of dimensionality on the heat transport in SiGe and other layered structures. I also participate on the characterization of organic thermoelectric materials for evidencing the critical phenomena and the relation
structure/properties which allow enhancing the thermoelectric figure-of-merit ZT. Extensive studies of the influence of doping, synthesis routes and chemical composition of soft matter on the properties of charges, phonon transport and on the intrinsic properties of the polymers are carried out. I am particularly interested in hybrid structures, for example of colloidal semiconductor QDs in polymeric matrices. The modifications of the dielectric function due to low-dimensional quantum confinement effects are extracted from ellipsometric investigations. Raman scattering and photoluminescence allow to characterize the changes of the QDs from the solution to the hybrid film.
Another ongoing research is the use of tensile strained Ge on Si substrates for monolithically integrated optoelectronics. Due to the indirect band gap, Ge is a bad light emitter. However, Ge can be turned into a “direct” gap material by the controlled application of sufficiently large tensile stress. We have started experiments on tensile strained Ge layers deposited by MBE and patterned using optical lithography and etching to fabricate suspended micro-structures in which tensile strain in Ge can be concentrated. My main contribution is to grow and improve the starting structures in connection with their light emitting properties and their application as sensors and also study the influence of all parameters including doping on the induced strain and resulting optical properties. Quite recently, I have started to work in photonic crystals, which
give rise to a variety of applications such as absorbers, waveguides, and light filters. In particular, I am working in the optimization of plasmonic crystals as SERS substrates.
October 1979 – June 1984. Bachelor in Physics at the Universitat Autònoma de Barcelona, Spain.
September 1984 – April 1985. Master Thesis in Physics by the Universitat Autònoma de Barcelona, Spain. Director Prof. Jordi Pascual.
May 1985 – October 1989. Ph. D. research fellowship at the Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
Dr rer Nat (Ph. D. Thesis) at the University of Stuttgart, Germany. Director Prof. Manuel Cardona.
Epitaxial growth and optical characterization of semiconductors, especially semiconductor nanostructures, both inorganic and organic.
Spectroscopic ellipsometry of multilayered and anisotropic materials.
Raman scattering, SERS.