Auger and Carrier Trapping Dynamics in Core/Shell Quantum Dots Having Sharp and Alloyed Interfaces by Gary Beane, Ke Gong, David F. Kelley.
The role of interface sharpness in controlling the excited state dynamics CdSe/ZnSe core/shell particles is examined here. Particles composed with 2.4-4.0 nm diameter cores and approximately 4 monolayer shells are synthesized at relatively low temperature, ensuring a sharp core-shell interface. Subsequent annealing results cadmium zinc interdiffusion, softening TEM imaging absorption spectra reveal that no change particle sizes. Annealing 5-10 blue shift spectrum, which compared to calculated spectral shifts characterize extent metal interdiffusion. one- two-photon measured using time-resolved spectroscopy. We find biexcitons undergo biexponential decays, fast slow decay times differing by about an order magnitude. relative magnitudes components depend on interface, larger component amplitudes associated assigned Auger recombination band edge carriers holes trapped defects produced lattice strain. these softens thereby reduces amount strain diminishes magnitude component. time constant biexciton changes only slightly upon