Self-ordering of Ge islands on Si substrates mediated by local strain fields

We have fabricated linear chains and two-dimensional arrays of Ge islands b y self-assembling and self-ordering processes on vicinal Si substrates. Ste p bunches and stripe-like strain fields caused by underlying Si/SiGe multil ayers with periodic wire-like accumulations at step edges induce an alignme nt of Gr islands. Repulsion of neighboring islands is caused by overlapping short-ranged strain fields surrounding partially strain relaxed dots and d efines a minimum island separation. A periodic array of wires forming withi n the multilayer serves as a self-organized template for two-dimensionally ordered Ge islands with a lateral period of 120 nm which is comparable to t he island size.