Spatio-Temporal Dynamics of Carrier Capture Processes: Simulation of Optical Signals

Abstract

We perform simulations of time-resolved optical experiments of carrier-capture processes in a quantum wiredot system. Scattering of charge carriers with optical phonons of the quantum wire can result in transitions from the continuum states of the quantum wire to discrete states of the quantum dot. We treat the scattering of carriers with optical phonons within a Lindblad single-particle approach. By considering the coupling of carriers to a light field we are able to simulate pump-probe experiments which are shown to be capable of measuring the captured populations. We further discuss the influence of the Coulomb interaction on the obtained spectra.

Phonon-mediated exciton capture in Mo-based transition metal dichalcogenides

“…This, however, does not affect the capture dynamics since the localized states are far away from the simulation boundary. The spatiotemporal dynamics shows, that the capture happens only locally, in consistency with previous findings on the locality of capture processes in systems of lower dimensionality [25,27,28,62]. Further capture into the localized state occurs when density from the outer regions of the sample travel onto the potential leading to the gradual increase of captured excitons in Fig.…”

Theory of coherent pump–probe spectroscopy in monolayer transition metal dichalcogenides

“…All material parameters are found in table A1. In contrast to conventionally studied semiconductors with interband transitions near the Γ valley such as GaAs [71,[109][110][111][112][113][114][115][116][117], monolayer TMDCs show a multitude of different kinds of intra-and intervalley interactions owing to the simultaneous occurrence of energetically degenerate direct band gaps at the non-equivalent corners K and K of the first Brillouin zone.…”

Spatiotemporal dynamics of Coulomb-correlated carriers in semiconductors

“…While the ultrafast carrier dynamics including coherent and incoherent excitons has been extensively studied for homogeneous excitations [16][17][18][19], inhomogeneous treatments are more complicated. The aspect of spatiotemporal dynamics of photoexcited carriers on ultrashort time-and length scales has been studied either in the limit of low densities where Hartree-Fock approximations are applicable [20][21][22][23][24][25] or in the limit of an exact number of carriers taken as an initial condition [26,27]. While the treatment of the low-density case revealed the dynamics of the carrier excitation and the fundamental carrier and polarization transport after excitation, the latter underlines the effects of carrier correlations leading to strong deviations from the free-carrier behavior when treating correlated particles.…”