Experiments and analysis of the two-step growth of InGaAs on GaAs substrate.

The two-step growth technique was introduced to solve the high lattice mismatch (5.6%) between In0.78Ga0.22As and GaAs substrate, and the mechanism of dislocation density reduction by a low-temperature buffer (LT-buffer) was investigated experimentally. For different thicknesses of LT-buffer layers, the surface morphology and microstructure were investigated, and the residual strain and dislocation density of the In0.78Ga0.22As epitaxial layer were studied by XRD, Raman spectroscopy and TEM. We proposed a mechanism explaining the dislocation density reduction during the two-step growth process by the LT-buffer. Also, the experimental results support our conclusion and verify the mechanism we presented. [ABSTRACT FROM AUTHOR]