Structural properties of MOVPE-grown ZnMgSe epilayers and ZnSe/ZnMgSe MQWs on (100) GaAs

The structural characterisation of MOVPE-grown ZnMgSe and ZnSe/ZnMgSe multiple quantum wells (MQWs) is reported. Zn0.83Mg0.17Se epilayers and 6 periods ZnSe/Zn0.83Mg0.17Se MQWs having 4.5 nm thick ZnSe wells and 10.5 nm thick alloy barriers were deposited on (1 0 0) GaAs after a thin pseudomorphic ZnSe buffer. No macroscopic misorientations between ZnMgSe epilayers and GaAs lattice has been observed, but a broadening of the alloy (4 0 0) peak indicates the occurrence of extended defects. Reciprocal space map (RSM) measurements of a Zn0.83Mg0.17Se epilayer show a slight asymmetry of the alloy peak along the growth direction, ascribed to an inhomogeneous relaxation, Diffraction patterns recorded in asymmetrical configuration indicate almost no relaxation of the MQWs structure, within the technique sensitivity. RSMs in the vicinity of the (4 0 0) lattice point show a characteristic diffuse scattering around the MQW satellite peaks, indicating that the MQWs structure is beyond the onset of plastic relaxation.