Strain effect and atomic arrangement studies in ZnTe/GaAs lattice-mismatched heterostructures

Abstract

Transmission electron microscopy (TEM) measurements were performed to investigate the lattice mismatch and the microstructural properties of a ZnTe layer grown on a GaAs (100) substrate. The results of the TEM images and the electron diffraction patterns showed that there was a large lattice mismatch between the ZnTe epitaxial layer and the GaAs substrate and that 60 degrees and 90 degrees dislocations, together with stacking faults, were observed near the ZnTe/GaAs heterointerface. When a 1.5 mum ZnTe layer was grown on the GaAs substrate, the ZnTe layer became a defect-free epitaxial film. The ZnTe epitaxial film grown on the GaAs substrate receives a compressive strain of -0.61 %, and possible atomic arrangements of the 60 degrees and 90 degrees dislocations are discussed on the basis of the high-resolution TER I results. The results indicate that the ZnTe layer grown on the GaAs substrate plays an important role as a buffer for the growth of CdxZn1-xTe/ZnTe quantum well structures by eliminating the defects generated due to the lattice mismatch.