Investigating the chemical and morphological evolution of GaAs capped InAs/InP quantum dots emitting at 1.5 μm using aberration-corrected scanning transmission electron microscopy

The emission wavelength of InAs quantum dots grown on InP has been shown to shift to the technologically desirable 1.5 μm with the deposition of 1–2 monolayers of GaAs on top of the quantum dots. Here, we use aberration-corrected scanning transmission electron microscopy to investigate morphological and compositional changes occurring to the quantum dots as a result of the deposition of 1.7 monolayers of GaAs on top of them, prior to complete overgrowth with InP. The results are compared with theoretical models describing the overgrowth process.

► InAs/InP quantum dots (QDs) overgrown with GaAs were studied here. ► Deposition of GaAs on top of InAs/InP QDs tunes the emission wavelength to 1.5 μm. ► QDs were studied by atomic-resolution scanning transmission electron microscopy. ► The effect of GaAs on the morphology of the QDs was investigated. ► The results were direct evidence for theoretical models of the growth process.