Self-alignment of self-assembled InAs quantum dots

The lateral self-alignment properties of self-assembled InAs quantum dots (QDs) on a conventional GaAs (1 0 0) substrate by molecular beam epitaxy were investigated. The shape and optical properties of QDs were investigated by atomic force microscopy, transmission electron microscope, and photoluminescence (PL). Attempts were made to grow InAs-QDs using the In-interruption growth technique, in which the In flux was periodically interrupted. QDs grown without using the In-interruption growth technique were grown randomly on all regions. On the other hand, in the case of QDs grown using the In-interruption growth technique, QDs were self-aligned at the boundary between bright and dark regions, the PL intensity was increased and the PL peak position of QDs were red-shifted to 1300 nm. This represent a new technique for growing self-aligned QDs because no extra processing such as electron-beam lithography, V-grooves and surface modification by scanning tunneling microscopy is needed, and aligned QDs can be grown in situ on conventional GaAs substrates.