Composition modulation in lattice matched Zn1−xMgxSySe1−y/ZnSe buffer layer/GaAs heterostructures

[100] composition modulation as well as [101] and [1̄01] tweed strain contrast were observed in lattice matched Zn1−xMgxSySe1−y epitaxial films grown on ZnSe buffer layers. The composition modulation corresponds to regions with different S and Mg concentration in a direction perpendicular to the growth direction. Very high quality lattice matched Zn1−xMgxSySe1−y films with a ZnSe quantum well were grown on As stabilized GaAs substrates exposed to Zn for a short time. The density of defects in these samples was less than 5×104/cm2. Other samples showed rough interfaces and high densities of Frank partial dislocations. The roughness is believed to result from an As-rich GaAs surface produced after the desorption of oxide under As overpressure.