Long-range ordered lines of self-assembled Ge islands on a flat Si (001) surface

Self-assembled growth in combination with prepatterning yields ordered line s of Ge islands on a planar Si (001) surface. The self-assembled Ge nanostr uctures are grown on top of a 15-period Si/SiGe superlattice, which is depo sited on a prepatterned Si substrate. The pattern consists of 10 nm deep tr enches with a period of 250 nm. The superlattice translates the surface mod ulation of the substrate into a strain-field modulation at the growth front of the superlattice. This strain field modulation provides the template fo r the ordered nucleation of self-assembled Ge islands. Our method gives ris e to the long-range ordering of perfectly passivated nanostructures and can in principle be applied to any other strained material system. (C) 2000 Am erican Institute of Physics. [S0003-6951(00)00747-6].