Transformation of the defect structure of InGaAs and InAlAs metamorphic buffer layers depending on indium concentration

Abstract

A study of samples grown by molecular beam epitaxy using the technology of InxAl1-xAs or InxGa1-xAs metamorphic buffer layer formation on GaAs (001) substrate was performed by transmission electron microscopy. The 1 μm thick buffer layers with square-root dependence of In content on buffer layer thickness were studied in plan-view and cross-section geometries. The results demonstrate cascade step-wise relaxation of misfit strain along buffer layer thickness with the reduction of dislocation density to less than 10−6 cm−2 at the subsurface region. An inhomogeneous distribution of dislocations observed on plan-view TEM images is explained by overlap of split-level dislocation networks with different periods.