Molecular beam epitaxy growth of ZnxCd(1−x)Se/Znx′Cdy′Mg(1−x′−y′)Se-InP quantum cascade structures

We report growth by molecular beam epitaxy of a ZnxCd(1−x)Se/Znx′Cdy′Mg(1−x′−y′)Se quantum cascade (QC) structure that was designed for electroluminescence (EL) at ∼4.5 μm. The QC active region is comprised of a two-well asymmetric coupled quantum well (ACQW) structure, which was thoroughly investigated to establish the growth conditions for the QC structure. After growth of several ACQW test samples, the conditions for growth were optimized for the QC structure. In-situ RHEED, photoluminescence (PL), high-resolution X-ray diffraction (HR-XRD) and Fourier transform infrared (FTIR) spectroscopy results were used for characterization. The QC structure grown under these conditions exhibited EL at 4.8 μm, in excellent agreement with the design value.