Dinâmica de elétrons e buracos fotoexcitados no limite de altas temperaturas

Abstract

A set of fifteen coupled non-llnear integro-differential equations was obtained for the study of photoexci ted electrons and holes dynamics in III-V semiconductors. A quantum transport theory obtained from Zubarev' s Nonequilibrium Statistical Operator Method, and from Bogoliubov's assumption of the existence of relaxation times for micro-information has been used. All of the possible interactions between carriers and phonons (intra and intervalley) were taken into account, as well as the carriers coulomb interaction. ln the scheme of central parabolic bands and in the limit of high temperatures, the set of integro-differential equations was reduced to five coupled differential equations. The equations system was solved for initial conditions characterizing three distinct situations: (i) the photoexcited hot electron and hole relaxation process; (ii) the heating of photoexcited cold electron and hole by a hot lattice; (ili) the hot-phonon effect on the photoexci ted carriers temporal dynamics. ln the first situation, it was shown that the heavy holes relax their energy excess faster than the electrons. One conclude that the e-h coulombic interaction could be an important mechanism for the increase (decrease) of the hot electron (hole) energy dissipation rate. ln the second situation, it was shown that the heating of cold carriers by the action of the hot lattice occurs slower than the hot carrier cooling process. This process is strongly influenced by the interaction between phonons. In the third situation, it was shown that, with an effe􀀯tlve temperature model for the phonons, a strong decrease of the carrler relaxation rate of energy is obtained when the LO-phonon temperature lncrease.