Growth Process and Photoluminescence Properties of In‐Plane Ultrahigh‐Density InAs Quantum Dots on InAsSb/GaAs(001) (Phys. Status Solidi B 4/2018)

In‐plane ultrahigh‐density InAs quantum dots (QDs) were grown by Oikawa et al. (article no. 1700307) on an InAsSb wetting layer (WL) on GaAs(001) substrate by molecular beam epitaxy. At the initial growth of InAs, elongated small two‐dimensional (2D) islands were formed on the InAsSb WL. As the InAs growth proceeded, 3D dots were spontaneously formed, and the underlying 2D terrace narrowed. In addition, surface atoms of the 2D layer desorbed because of strain relaxation. From analysis of the 3D‐island volume, it was found that surface atoms that had desorbed from the 2D layer were re‐incorporated into the 3D islands. The dot density reached a highest value of 1 × 1012 cm−2. Furthermore, the photoluminescence (PL) spectra of in‐plane ultrahighdensity InAs dots with small sizes were analyzed to confirm a zero‐dimensional electron system. The PL peak energy and linewidth discontinuously changed at 1.6 monolayer (ML) of total coverage (InAs + InAsSb), which was the critical thickness of 2D–3D growth mode transition. Particularly, the PL peak energy was almost proportional to the −0.27th power of the average volume of 3D islands, indicating conical‐shape QDs.