Effects of In_0.82Ga_0.18As/InP double buffers design on the microstructure of the In_0.82G_0.18As/Inp heterostructure

In order to reduce the dislocation density and improve the performance of high indium content In_0.82Ga_0.18As films, the design of double buffer layers has been introduced into the In_0.82Ga_0.18As/InP heterostructure. Compared with other buffer layer structures, we introduce an InP thin layer, which is the same as the substrate, into the In_0.82Ga_0.18As/InP heterostructure. The epitaxial layers and buffer layers were grown by the low-pressure metalorganic chemical vapor deposition (LP-MOCVD) method. In this study, the surface morphology and microstructures of the heterostructure were investigated by SEM, AFM, XRD and TEM. The residual strains of the In_0.82Ga_0.18As epitaxial layer in different samples were studied by Raman spectroscopy. The residual strain of the In_0.82Ga_0.18As epitaxial layer was decreased by designing double buffer layers which included an InP layer; as a result, dislocations in the epitaxial layer were effectively suppressed since the dislocation density was notably reduced. Moreover, the performance of In_0.82Ga_0.18As films was investigated using the Hall test, and the results are in line with our expectations. By comparing different buffer layer structures, we explained the mechanism of dislocation density reduction by using double buffer layers, which included a thin InP layer.