Growth Process and Photoluminescence Properties of In‐Plane Ultrahigh‐Density InAs Quantum Dots on InAsSb/GaAs(001)

InAs is grown on InAsSb/GaAs(001) by molecular beam epitaxy (MBE). At the initial growth of InAs, elongated small two‐dimensional (2D) islands are formed on the InAsSb wetting layer (WL). As the InAs growth proceeded, 3D dots are spontaneously formed, and the underlying 2D terrace narrows. In addition, surface atoms of the 2D layer desorbed because of the strain relaxation. The 3D dot volume is larger than that estimated from the supply amount. From these results, it is found that surface atoms desorbed from the 2D layer are re‐incorporated into 3D islands. The dot density reaches at 1 × 1012 cm−2. The photoluminescence (PL) peak energy and full width at half maximum discontinuously changed at the critical coverage for 2D–3D growth mode transition. Particularly, the PL peak energy is almost proportional to the −0.27‐th power of the average volume of 3D islands. It reveals that the carriers in these 3D islands have properties based on the 0D electron system, despite of in‐plane ultrahigh density and small sizes. In addition, the relationship between PL intensity and quantum‐dot density is evaluated. In‐plane ultrahigh‐density InAs quantum dots (QDs) were grown on InAsSb/GaAs(001) by molecular beam epitaxy. The authors analyzed the surface structure of InAs islands on InAsSb wetting layer and studied the growth process of ultrahigh‐density InAs QDs in detail. The QD volume dependence of the photoluminescence peak energy revealed the zero‐dimensional electron system of those QDs, despite of in‐plane ultrahigh density and small sizes.