Investigation of the Spatial Distribution of Excess Arsenic in an LT-GaAs Layer by Rocking Curve Imaging

Rocking curve imaging has been used for the first time to plot maps of excess arsenic spatial concentration in the LT-GaAs layer in a GaAs/AlAs/AlGaAs/LT-GaAs(100) heterostructure, grown by molecular-beam epitaxy. An area detector with a matrix size of 14 × 14 mm and a resolution of 55 µm was used to localize regions with different concentrations of excess As atoms: from 0.86 × 1020 to 0.96 × 1020 cm–3. The concentration of excess arsenic was determined by analyzing the difference in the angular positions of the diffraction peaks from the GaAs substrate and the LT-GaAs layer, which is due to the increase in the unit-cell parameter, caused by incorporation of arsenic atoms into gallium sites (AsGa).