Evaluation of the composition of the interlayer at the inverted interface in InGaP/GaAs heterojunctions

An evaluation of the composition of the extra interlayer at the GaAs-on-InGaP inverted interface in MOVPE grown InxGa1−xP/GaAs heterostructures has been carried out by chemically sensitive (200) dark field TEM in the kinematical approximation. X-ray diffraction measurements have also been performed that showed that the extra interlayer had a negative strain to GaAs. In combination with this result the (200) dark field measurements allowed to establish that the extra interlayer can be either GaAs1−yPy (y=0.55) or InxGa1−xAs1−yPy with 0