Site control of self-organized InAs dots on GaAs substrates by in situ electron-beam lithography and molecular-beam epitaxy

We studied a site-control method for self-organized InAs quantum dots on GaAs substrates by a combination of in situ electron-beam (EB) lithography and molecular-beam epitaxy (MBE) using an ultrahigh-vacuum multichamber system. Small and shallow holes were patterned on a MBE-grown GaAs (001) surface by in situ EB writing and Cl2-gas etching. When more than a 1.4 monolayer of InAs was applied to the patterned surface, In(Ga)As dots were preferentially self-organized in the holes while dot formation around the holes was sufficiently suppressed. When we further increased the amount of InAs, the dots enlarged remarkably, presumably due to a stress-relaxation effect.