Double-Helical Silicon Microtubes


  • We thank S. Ito for preparing a thin section of the sample and for TEM observations. We are also grateful to Dr. Y. Hayashi and Prof. R. Kainuma for their help with the digital optical microscope (KEYENCE, VHX-1000) and the scanning electron microscope (SEM, KEYENCE, VE-9800). This work was supported in part by a Grant-in-Aid for Young Scientists (Start-up) from the Ministry of Education, Culture, Sports, Science and Technology (No. 20860016).


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A new twist on semiconductors: The evaporation of Na from ionic intermetallic NaSi at 800 °C leads to the formation of double-helical silicon microtubes. The tubes have nanogranular or smooth surfaces and a twinned structure with voids in the tube wall. A mechanism is proposed for the formation of the double-helical microtubes.