Self-organization of nanoscale Ge islands in SirGerSi 113/ multilayers

Multilayers of coherent Ge islands and Si spacer layers were grown on Si 113. substrate at 400 and 4508C by molecular-beam epitaxy. The islands grown on the substrates have a wire-like shape with 1594facets. The islands become more uniform as layer number increases when the growth temperature is 4008C. When the temperature is 4508C, the island shape changes from wire-like in the 1st Ge layer to dash-like in 6th Ge layer. The self-organized Ge islands are vertically aligned at both temperatures. The temperature-dependent self-organization can be explained by considering that the filtering effect acts one-dimensionally at 4008C and two-dimensionally at 4508C as predicted theoretically. q1998 Elsevier Science B.V. All rights reserved.