Effective detection of spatio-temporal carrier dynamics by carrier capture

Abstract

The spatio-temporal dynamics of electrons moving in a 2D plane is challenging to detect when the required resolution shrinks simultaneously to nanometer length and subpicosecond time scale. We propose a detection scheme relying on phonon-induced carrier capture from 2D unbound states into the bound states of an embedded quantum dot. This capture process happens locally and here we explore if this locality is sufficient to use the carrier capture process as detection of the ultrafast diffraction of electrons from an obstacle in the 2D plane. As an example we consider an electronic wave packet traveling in a semiconducting monolayer of the transition metal dichalcogenide MoSe2, and we study the scattering-induced dynamics using a single particle Lindblad approach. Our results offer a new way to high resolution detection of the spatio-temporal carrier dynamics.

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

“…The possibility to conveniently address the K, K valley degree of freedom with light of opposite circular polarization allows to explore coupled spin-valley physics in these ultrathin materials [9][10][11][12][13][14][15][16]. Due to the strong Coulomb interactions, tightly bound electronhole pairs, referred to as excitons, dominate the optical properties of monolayer TMDCs below the single particle band gap [17][18][19][20] as investigated in time and momentum [21][22][23][24] as well as studied in the spatiotemporal dynamics [25][26][27][28][29][30].…”

Excitonic theory of doping-dependent optical response in atomically thin semiconductors

“…Concurrently, the simplicity of our theory allows further adaptations, for instance, to study the trion dynamics in optical wave mixing experiments [98][99][100][101][102] or photoluminescence [103][104][105][106] influenced by phonon-assisted relaxation phenomena [107,108]. Further perspectives could be to theoretically investigate the influence of doping on spatiotemporal dynamic effects not only in monolayer TMDCs [109][110][111][112][113][114][115][116] but also in other atomically thin semiconductors like hybrid perovskites [117][118][119].…”

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

“…In conventional semiconductors it was shown in quantum kinetic calculations that the presence of the polaron, especially within the continuum of states, in combination with the intrinsic local nature of capture strongly broadens the energy selection rule [25,26,51]. While such an energetic broadening can be incorporated in simplified models to enable simulations in systems of low symmetry [28,65], its quantitative value is of quantum kinetic nature. Therefore, it is interesting to study this effect in TMDCs and quantify the polaron-related energy broadening in TMDCs.…”