TEM AND XRD STUDY OF STRAIN RELEASE IN GAAS/INP AND INP/GAAS HETEROSTRUCTURES GROWN BY MOVPE

The strain release has been studied by high resolution X-ray diffraction in highly mismatched Atomic Layer MOVPE InP/GaAs and conventional MOVPE GaAs/InP grown heterostructures. The InP/GaAs structures follow the predictions of the equilibrium theory, while the strain release in the GaAs/InP structures occurs at slightly larger thickness values. ALE achieves 2-Dimensional growth of InP from thickness of 5 nm while growth islands are still present in 20 nm thick GaAs layers. The crystal defects have been investigated by transmission electron microscopy and their characteristics have been correlated with the strain release. No differences in the defect density and structure have been observed between the two systems.