Room-Temperature Yellow Emission of a High Cd Content (x = 0.70), Highly Strained, Layer-by-Layer Grown Zn_1−xCd_xSe/ZnSe Quantum Well

The results of the growth and characterization of an 8 monolayers (MLs) thick Zn_1−xCd_xSe/ZnSe quantum well (QW) with quite high Cd content (x = 0.70) are presented. At room temperature (RT), the QW presents yellow excitonic emission at 2.179 eV (569 nm, same color as the yellow line of a Kr ion laser). Despite the large Cd content, the RT photoluminescence spectrum shows a well-defined, symmetric excitonic peak with relatively narrow full width at half maximum, indicating a good structural quality of the QW that is attributed to the sequential layer-by-layer growth mode achieved by the use of the submonolayer pulsed beam epitaxy (SPBE) technique. The ZnSe barriers are grown by molecular beam epitaxy (MBE); the QW heterostructure is deposited on top of a GaAs(001) substrate at 275 °C. Scanning transmission electron microscopy indicates a homogeneous smooth QW layer. The evolution of the excitonic emission energy with increasing temperature in the 19–300 K range shows the well-known S-shaped behavior that is interpreted in terms of exciton migration.