ACTA

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

S.V. Gronin^a, S.V. Sorokin^a, D.R. Kazanov^a,b, I.V. Sedova^a, G.V. Klimko^a, E.A. Evropeytsev^a, S.V. Ivanov^a
^aIoffe Physical-Technical Institute of RAS, St.-Petersburg, Russia
^bSt.Petersburg State Polytechnical University, St.-Petersburg, Russia

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This paper reports on theoretical calculations and fabrication by molecular beam epitaxy of wide-gap II-VI heterostructures emitting in the "true" yellow range (560-600 nm) at room temperature. The active region of the structures comprises CdSe quantum dot active layer embedded into a strained Zn_1-xCd_xSe (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 Zn_1-xCd_xSe quantum well thicknesses (d ≈ 2-4 nm) reducing efficiently the emission wavelength, while the variation of x (0.2-0.5) has much stronger effect. 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 ZnS_0.17Se_0.83/ZnSe superlattice were introduced to compensate the compressive stress induced by the Zn_1-xCd_xSe quantum well. The graded-index waveguide laser heterostructure with a CdSe/Zn_0.65Cd_0.35Se/Zn(S,Se) quantum dot-quantum 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.

DOI: 10.12693/APhysPolA.126.1096
PACS numbers: 81.15.Hi, 78.55.Et, 78.67.Hc, 68.65.Fg