P. Renucci

Probing carrier dynamics in nanostructures by picosecond cathodoluminescence

Picosecond and femtosecond spectroscopy allow the detailed study of carrier dynamics in nanostructured materials. In such experiments, a laser pulse normally excites several nanostructures at once. However, spectroscopic information may also be acquired using pulses from an electron beam in a modern electron microscope, exploiting a phenomenon called cathodoluminescence. This approach offers several advantages. The multimode imaging capabilities of the electron microscope enable the correlation of optical properties (via cathodoluminescence) with surface morphology (secondary electron mode) at the nanometre scale. The broad energy range of the electrons can excite wide-bandgap materials, such as diamond- or gallium-nitride-based structures that are not easily excited by conventional optical means. But perhaps most intriguingly, the small beam can probe a single selected nanostructure. Here we apply an original time-resolved cathodoluminescence set-up to describe carrier dynamics within single gallium-arsenide-based pyramidal nanostructures with a time resolution of 10 picoseconds and a spatial resolution of 50 nanometres. The behaviour of such charge carriers could be useful for evaluating elementary components in quantum computers, optical quantum gates or single photon sources for quantum cryptography.

Exciton radiative lifetime in transition metal dichalcogenide monolayers

We have investigated the exciton dynamics in transition metal dichalcogenide monolayers using time-resolved photoluminescence experiments performed with optimized time resolution. For

Excitonic Linewidth Approaching the Homogeneous Limit in MoS2 -Based van der Waals Heterostructures

\mathrm{MoS}{\mathrm{e}}_{2}

Robust quantum dot exciton generation via adiabatic passage with frequency-swept optical pulses.

monolayer, we measure

High brightness picosecond electron gun

{\ensuremath{\tau}}_{\mathrm{rad}}^{0}=1.8\ifmmode\pm\else\textpm\fi{}0.2\phantom{\rule{0.16em}{0ex}}\mathrm{ps}

Room-temperature optical orientation of the exciton spin in cubic Ga N ∕ Al N quantum dots

at

Enabling valley selective exciton scattering in monolayer WSe2 through upconversion.

T=7\phantom{\rule{0.16em}{0ex}}\mathrm{K}

MgO thickness dependence of spin injection efficiency in spin-light emitting diodes

that we interpret as the intrinsic radiative recombination time. Similar values are found for

Spin dynamics in dilute nitride semiconductors at room temperature

\mathrm{WS}{\mathrm{e}}_{2}

Large and robust electrical spin injection into GaAs at zero magnetic field using an ultrathin CoFeB/MgO injector

monolayers. Our detailed analysis suggests the following scenario: at low temperature