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

Abstract

The two-step growth technique was introduced to solve the high lattice mismatch (5.6%) between In_0.78Ga_0.22As 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 In_0.78Ga_0.22As 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.