Direct formation of InAs quantum dots grown on InP (001) by solid-source molecular beam epitaxy

We have developed a growth process that leads to the direct formation of self-assembled InAs quantum dots on InP(001) by solid-source molecular beam epitaxy avoiding the previous formation of quantum wires usually obtained by this technique. The process consists of a periodically alternated deposition of In and As correlated with $InAs(4×2)↔(2×4)$ surface reconstruction changes. Based on the results obtained by in situ characterization techniques, we propose that the quantum dots formation is possible due to the nucleation of In droplets over the $InAs(4×2)$ surface during the In deposition step and their subsequent crystallization under the As step.