Fig. 2: Nanoscale structure of ELM-QDs.
From: Efficient single-photon emission via quantum-confined charge funneling to quantum dots
a Cross-sectional TEM image of a representative single Al0.2Ga0.8As funnel at ×80,000 magnification showing the central area of the disk and two sides of the ring-shaped ridge. b Cross-sectional TEM images of LDE GaAs QDs at higher magnification (×150,000, QD location in (a) is indicated with red boxes). Dark streaks (indicated with yellow arrows) show cross-sections of Al puddles formed near the QDs. c Ga and Al composition along line scans A and B in (a) obtained with EDS. The Ga (Al) composition is shown with the red (blue) line. d Atomic force microscopy (AFM) image of a typical ELM-QD. e Topography and the corresponding bandgap energy profile along two AFM line scans are indicated by the blue and red dashed lines in (d). Bandgap energy in the funnel is calculated using the AlGaAs disk thickness profiles and the Al composition.
