Structural and chemical investigation of InAs/GaAs nanostructures by transmission electron microscopy

report on the transmission electron microscopy characterization of InAs Stranski-Krastanov layers grown on GaAs (001) by molecular beam epitaxy at growth temperatures of 480 and 530 degreesC. Chemically sensitive reflections are used for the evaluation of the composition. The different influence of strain effects on the imaging with either the (002) or the (020) reflection is discussed. The considerations show that the (002) reflection can be used for an accurate measurement of the In concentration. The evaluation of concentration profiles of the wetting layers reveal a segregation probability of R = 0.77 +/- 0.02 for T-G = 480 degreesC and R = 0.82 +/- 0.02 for T-G = 530 degreesC.