CdSe/ZnCdSe Quantum Dot Heterostructures for Yellow Spectral Range Grown on GaAs Substrates by Molecular Beam Epitaxy

This paper reports on theoretical calculations and fabrication by molecular beam epitaxy of wide-gap IIVI heterostructures emitting in the true yellow range (560600 nm) at room temperature.The active region of the structures comprises CdSe quantum dot active layer embedded into a strained Zn1-xCdxSe (x = 0.2-0.5)quantum well surrounded by a Zn(S,Se)/ZnSe superlattice.Calculations of the CdSe/(Zn,Cd)Se/Zn(S,Se) quantum dot quantum well luminescence wavelength performed using the envelope-function approximation predict rather narrow range of the total Zn1-xCdxSe quantum well thicknesses (d ≈ 2-4 nm) reducing eciently the emission wavelength, while the variation of x (0.20.5) has much stronger eect.The calculations are in a reasonable agreement with the experimental data obtained on a series of test heterostructures.The maximum experimentally achieved emission wavelength at 300 K is as high as 600 nm, while the intense room temperature photoluminescence has been observed up to λ = 590 nm only.To keep the structure pseudomorphic to GaAs as a whole the tensile-strained surrounding ZnS0.17Se0.83/ZnSesuperlattice were introduced to compensate the compressive stress induced by the Zn1-xCdxSe quantum well.The graded-index waveguide laser heterostructure with a CdSe/Zn0.65Cd0.35Se/Zn(S,Se)quantum dotquantum well active region emitting at λ = 576 nm (T = 300 K) with the 77 to 300 K intensity ratio of 2.5 has been demonstrated.