Le groupe de Spectroscopie Théorique du LSI reçoit la visite du Dr Andrea Marini du Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), Italie. Dr Marini est membre du European Theoretical Spectroscopy Facility depuis sa création en 2007 et coordinateur du code Yambo. Il présentera lors de son séminaire ses travaux sur la relaxation des porteurs ultra-rapides dans le silicone.
Abstract: A novel approach based on the merging of the out-of-equilibrium Green’s function method with the Density-Functional-Theory is used to describe the ultra-fast carriers relaxation in Silicon. The results are compared with recent two photon photo-emission measurements showing that the state-of-the-art interpretation of the carrier relaxation in terms of L->X inter-valley scattering is not correct. The ultra-fast dynamics measured experimentally is, instead, due to the scattering between degenerate L states that is activated by the non symmetric population of the conduction bands induced by the laser field. This ultra-fast relaxation is, then, entirely due to the specific experimental setup and it can be interpreted by introducing a novel definition of the quasi-particle lifetimes in an out-of-equilibrium context.