Probing carrier dynamics in nanostructures by picosecond cathodoluminescence

摘要: Picosecond and femtosecond spectroscopy allow the detailed study of carrier dynamics in nanostructured materials1. 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 modern microscope, exploiting phenomenon called cathodoluminescence. This approach offers advantages. The multimode imaging capabilities microscope enable correlation optical properties (via cathodoluminescence) with surface morphology (secondary mode) nanometre scale2. broad energy range electrons can excite wide-bandgap materials, as diamond- or gallium-nitride-based structures that are not easily excited by conventional means. But perhaps most intriguingly, small probe single selected nanostructure. Here we apply original time-resolved cathodoluminescence set-up to describe within gallium-arsenide-based pyramidal nanostructures3 time resolution 10 picoseconds spatial 50 nanometres. behaviour charge carriers could useful for evaluating elementary components quantum computers4,5, gates6 photon sources7,8,9 cryptography10.