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

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Abstract
We study the energetics of island formation in Stranski-Krastanow growth of highly mismatched heteroepitaxy within a parameter-free approach. It is shown that the (frequently found) rather narrow size distribution of the self-assembled coherent islands can be understood as the result of the system being trapped in a constrained equilibrium state with a fixed island density. If allowing for variations of the island density, we find that larger islands combined with a lower island density are more stable; this implies that Ostwald ripening will take place on time scales sufficiently long for exchange 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 depends on the island size, i.e., an island with larger volume has a higher value of the height-to-base ratio.