Selective electrochemical profiling of threading defects in mismatched heteroepitaxial systems

The defect structure in MBE-grown (100) InGaAs/GaAsheteroepitaxial systems is studied by selective electrochemical
(anodic) etching. The In content and layer thicknesses are
between 0.03-0.3 and 0.02-5 µm respectively (above critical
layer thickness). Different aqueous electrolytes and bias
voltages are tried to optimise the etching conditions. By
incremental layer removal, we mapped the depth profile of the
dislocation density. The density of defects is inversely
proportional to the layer thickness and increases with misfit.
The results are compared to theoretical models.