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AM, Kamins TI, Ohlberg DAA, Williams RS: Shape transition of germanium nanocrystals on a silicon (001) surface from pyramids to domes. Science 1998, 279:353.CrossRef 29. Zhou W, Wang SH, Ji T, Zhu Y, Cai Q, Hou XY: Growth of erbium silicide nanowires on Si(001) surface studied by scanning tunneling microscopy. Jpn J Appl Phys 2059, 2006:45. 30. Weir RD: Thermophysics of advanced engineering materials. Pure Appl Chem 1999, 71:1215.CrossRef Competing interests click here The authors declare that they have no competing interests. Authors’ contributions ZQZ designed the project of experiments and drafted the manuscript. WCL and XYL carried out

the growth of MnSi~1.7 nanowires and STM measurements. GMS performed the SEM observations. All authors read and approved the final manuscript.”
“Background One-dimensional (1D) ZnO nanostructures (e.g., nanowires, nanorods,

and nanotubes) are promising with extensive applications in nanoelectronics and nanophotonics due to their efficient transport of electrons and excitons [1]. In recent years, increasing attention has been paid to three-dimensional (3D) hierarchical ZnO architectures which derived from 1D nanostructures as building blocks based on various novel applications [2–6]. To date, different kinds of hierarchical branched ZnO nanostructures, including nanobridges [7], nanoflowers [2, 8], rotor-like structures [9], and find more nanotubes surrounded by well-ordered nanorod structures [10], have been reported by using either solution-phase or vapor-phase method. However, these processes often require high temperature, complex multi-step process, or introduction of impurities by the templates or foreign catalysts in the reaction system. else Therefore, it is still a challenge to find a simple and controllable synthetic process to fabricate 3D hierarchical ZnO architectures with novel or potential applications. On the other hand, doping is a widely used method to improve the electrical and optical properties of semiconductors [11]. Copper, considered as a valuable dopant for the achievement of long-searched-for p-type ZnO [12], can serve not only as a luminescence activator but also as a compensator of ZnO [13]. In addition, Cu doping, leading to form donor-acceptor complexes, can induce a polaron-type ferromagnetic order in ZnO [14, 15].