Formation of directed self-assembled Ge/Si quantum dots

Directed self assembly of sub-10-nm Ge islands are candidates for producing laterally coupled quantum dot molecules with geometrically defined spin exchange couplings. We describe low-temperature magnetotransport measurements on small arrays of Ge islands grown on semi-insulating silicon substrates. The islands are created by a technique for precise nucleation of Ge islands using nanoscale SiC templates defined by direct-write electron-beam lithography.\footnote{O. Guise, J. Ahner, J. John T. Yates, V. Vaithyanathan, D. G. Schlom, J. Levy, Appl. Phys. Lett. $\bf{87}$, 1902 (2005).} Ge island arrays are coupled through ohmic contacts to the Si capping layer, and geometries are defined that are suitable for either vertical or lateral transport.