HIGH-RESOLUTION X-RAY-DIFFRACTION INVESTIGATIONS OF EPITAXIALLY GROWNZNSE GAAS LAYERS/

Single-crystalline ZnSe layers were grown by metal-organic vapour phas e and molecular beam epitaxy on (001) oriented GaAs substrates. The la ttice mismatch between layer and substrate at growth temperature cause s a strain in the layer material, which is relaxed by the nucleation o f misfit dislocations. The relaxation process starts at the critical t hickness, which depends on the growth conditions. The crystalline qual ity and the residual strain of the epilayers were investigated with a high-resolution x-ray diffractometer. Additionally, the intensity dist ribution of the scattered x-rays in the directions perpendicular and p arallel to the reciprocal lattice vector (004) was observed by a two-r eflection analyser crystal. For the system ZnSe/GaAs, this intensity d istribution depends on the degree of strain relaxation, which is depen dent on the layer thickness. The results are compared with transmissio n electron microscopy results.