Measurement of indium concentration profiles and segregation efficiencies from high-angle annular dark field-scanning transmission electron microscopy images

• We measured the indium concentration in an InGaAs/GaAs heterostructure by HAADF-STEM.
• Multislice calculations are carried out for [100] and [110] electron beam direction.
• [110] beam direction is better suited for concentration analysis.
• Segregation efficiencies are derived from concentration profiles.
• HAADF-STEM results are compared to CELFA measurement.

We investigated segregation of indium in an InxGa1−xAs/GaAs heterostructure via high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), where contrast strongly depends on the nuclear charges of the scattering atoms (Z-contrast). Indium concentration maps have been deduced from HAADF-STEM images by comparing normalized measured intensities with multislice simulations in the frozen lattice approach. Segregation coefficients were derived following the segregation model of Muraki et al. [1]. This is demonstrated for HAADF-STEM images recorded in [100] and [110] zone-axes. Determined indium concentrations and segregation coefficients are compared with results from composition analysis by lattice fringe analysis (CELFA) measurements and energy-dispersive X-ray analysis (EDX).