Yellow to green excitonic emission of nearly lattice-matched Zn1−zCdzSe/Zn1−xCdxSe/Zn1−yMgySe (z > x) quantum wells grown on GaAs(0 0 1)

Abstract

We report the results obtained from the design, epitaxial elaboration, and characterization of nearly lattice matched ZnCdSe quantum wells (QWs) with ZnMgSe barriers, specifically designed with emission in selected wavelengths in the yellow-green spectral range. The quantum wells were deposited on ZnSe/GaAs(0 0 1); ZnSe and ZnMgSe materials were grown by molecular beam epitaxy and ZnCdSe by submonolayer pulsed beam epitaxy in a sequential layer-by-layer mode. The three ZnCdSe layers of the QWs consist of a central region with i monolayers, 3 ≤ i ≤ 7, of Zn1−zCdzSe and at each side are 8 monolayers of Zn1−xCdxSe with Cd contents such that x < z in order to obtain a staggered potential. The barriers are made of Zn1−yMgySe adjusting the composition for lattice matching to the lateral regions of Zn1−xCdxSe, then, only the central quantum well region is lattice mismatched. The low temperature photoluminescence spectra of the QW heterostructures with 3, 4, 6 and 7 MLs central regions of Zn1−zCdzSe (z ∼ 0.77 ± 0.02) surrounded at each side by 8 MLs thick Zn1−xCdxSe layers (x = 0.25) presented excitonic emission at 14 K around 2.337, 2.292, 2.197 and 2.176 eV, respectively, that are in very good agreement with the model calculations. The only modification of the heterostructures was the layer thickness of the central region, indicating the feasibility of these QWs with minimized strain for excitonic emission in the yellow-green spectral region.