Uniform formation of two-dimensional and three-dimensional InAs islands on GaAs by molecular beam epitaxy

In order to fabricate uniform InAs quantum dots on a GaAs(001) substrate, the shape transition from two-dimensional (2D) to 3D islands was investigated in the case of molecular beam epitaxy via the Stranski-Krastanov growth mode. A critical lateral size of the 2D islands, just before the 3D formation, depended on the growth conditions.. In case of high growth rate and high arsenic pressure conditions, the critical size became small because of the multi nucleation mode. The stacked 2D islands induced a large fluctuation in the critical lateral size and caused large inhomogeneous broadening in the pyramidal 3D dots, which were covered by the stable facets. Therefore, the low growth rate and the low arsenic; pressure were effective conditions to achieve uniform 2D and 3D islands.