Abstract
Droplets grown by modified droplet epitaxy on non‐polar (11‐20) surfaces of InGaN epilayers on GaN have been seen to be associated with underlying ring‐like structures. This work discusses droplet etching as a possible mechanism for ring formation, and droplet creeping as a possible explanation for the droplets sitting askew of the ring centre. Transmission electron microscopy (TEM) analysis shows the droplets to move along the c‐axis, and indicates that they have a very high indium content.The image shows atomic force microscopy (AFM) data of a double‐ring structure, rendered in 3D.
Highlights
Nitride-based quantum dots (QDs) show promise as sources for single photon emission, enabling comparably high temperature emission [1] and access to the blue and green spectral region [2]
Status Solidi B published by WILEY-VCH Verlag GmbH & Co
It is our understanding that these smaller droplets form QDs upon capping, supported by a correlation of the density of such droplets measured by atomic force microscopy (AFM), and the density of bright cathodoluminescence (CL) features in the scanning electron microscope (SEM) [3]
Summary
Nitride-based quantum dots (QDs) show promise as sources for single photon emission, enabling comparably high temperature emission [1] and access to the blue and green spectral region [2]. The wurtzite structure of gallium nitride (GaN) results in significant electric fields across strained QDs grown in the c-plane orientation due to the very large piezoelectric constants. This reduces the radiative recombination efficiency due to the spatial separation of the electron and hole via the quantum confined Stark effect (QCSE). Atomic force microscopy (AFM) data reveal the presence of larger droplets and associated ring structures. These are under investigation to ascertain how they relate to the QD formation process, and how they themselves might be exploited as confinement centres
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