Structure and recombination in InGaAs/GaAs heterostructures

Abstract

The defect structure of lattice‐mismatched 1‐μm In_xGa_1−xAs (x≊0.12, misfit Δa/a≊8.5×10⁻³) epilayers on GaAs was studied with scanning cathodoluminescence (CL), transmission electron microscopy (TEM), high‐voltage electron microscopy, and scanning electron microscopy. CL shows that nonradiative recombination lines exist in the GaAs buffer layer as far as 4000 Å from the interface. The density of these defects is independent of substrate dislocation density. Plan‐view TEM analysis indicates that the majority of these dislocations in the buffer layer are sessile edge half‐loops. Cross‐sectional TEM shows that loops also extend into the InGaAs epilayer, but the majority of the loops are located on the buffer layer (substrate) side of the interface. A model is proposed to explain sessile edge <named-content...