InAs-dot/GaAs structures site-controlled by in situ EB lithography and self-organizing MBE growth

A novel site-control technique for InAs dots on GaAs has been demonstrated by a combination of in situ electron-beam (EB) lithography and self-organizing molecular-beam epitaxy (MBE) using an ultrahigh vacuum multi-chamber system. On an MBE-grown GaAs (001) surface, shallow holes of sub-micron size were patterned by in situ EB writing and Cl₂-gas etching. By supplying more than a 1.4 monolayer of InAs onto the patterned surface, In(Ga)As dots were preferentially self-organized in the holes, while dot-formation around the holes was sufficiently suppressed, due to the selectivity of In atom-incorporation in the (111)B-like slope in the hole. This indicates the usefulness of such techniques in fabricating arbitrarily arranged quantum-dot structures