title: Large-area ordered Ge-Si compound quantum dot molecules on dot-patterned Si (001) substrates.
abstract: We report on the formation of large-area ordered Ge-Si compound quantum dot molecules (CQDMs) in a combination of nanosphere lithography and self-assembly. Truncated-pyramid-like Si dots with {11n} facets are readily formed, which are spatially ordered in a large area with controlled period and size. Each Si dot induces four self-assembled Ge-rich dots at its base edges that can be fourfold symmetric along <110> directions. A model based on surface chemical potential accounts well for these phenomena. Our results disclose the critical effect of surface curvature on the diffusion and the aggregation of Ge adatoms and shed new light on the unique features and the inherent mechanism of self-assembled QDs on patterned substrates. Such a configuration of one Si QD surrounded by fourfold symmetric Ge-rich QDs can be seen as a CQDM with unique features, which will have potential applications in novel devices.
authors: State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, People's Republic of China.
authors: Hui
authors: H
authors: Lei
authors: Tong
authors: T
authors: Zhou
authors: Shuguang
authors: S
authors: Wang
authors: Yongliang
authors: Y
authors: Fan
authors: Zhenyang
authors: Z
authors: Zhong