Comparative cathodoluminescence and EBIC analysis of partially relaxed InGaAs/GaAs pin structures

EBIC and CL imaging of misfit dislocations in partially relaxed InxGa1-xAs/GaAs p-i-n junctions give contradictory results. The EBIC measurements agree with XRD and TEM observations and show that the dislocations are confined at the interface between the GaAs substrate and the first InGaAs epitaxial layer, that is 2.2mum from the free surface. A completely different scenario is obtained by CL when dark lines are visible both in panchromatic and monochromatic images with a beam energy as low as 3 keV. At this accelerating voltage the electron range is about 100 nm. The differences between the CL and the EBIC results are discussed.