Size, shape, and stability of InAs quantum dots on the GaAs(001) substrate

We study the energetics of island formation in Stranski-Krastanow growth of highly mismatched heteroepitaxy within a parameter-free approach. It is sh own that the (frequently found) rather narrow size distribution of the self -assembled coherent islands can be understood as the result of the system b eing trapped in a constrained equilibrium state with a fixed island density . If allowing for variations of the island density, we find that larger isl ands combined with a lower island density are more stable; this implies tha t Ostwald ripening will take place on time scales sufficiently long for exc hange of atoms between different islands to occur. Moreover, we show how to select the island size by controlling the growth conditions and the amount of deposited material. Our study also indicates that the island shape depe nds on the island size, i.e., an island with larger volume has a higher val ue of the height-to-base ratio.