HgTe/CdTe and HgSe/CdX (X = S, Se, and Te) Core/Shell Mid-Infrared Quantum Dots

Mid-infrared core/shell quantum dots are synthesized starting with HgTe and HgSe cores which emit around 5 μm with interband and intraband transitions, respectively. HgTe/CdTe and HgSe/CdX (X = S, Se, and Te) are grown by colloidal atomic layer deposition at room temperature. HgSe/CdSe is also grown by hot-injection. For films of the core/shells, even a two-monolayer shell leads to a vastly improved stability against annealing, with no observable changes up to the alloying temperatures of ∼180 °C for HgTe/CdTe and ∼250 °C for HgSe/CdX. The improvement in the photoluminescence remains however small for all systems. In this study across interband and intraband emissions, the brightest emitter at 5 μm is the intraband transition of HgSe/CdSe with a quantum yield of ∼10–3.