全国功能材料量子设计和量子物理研究生培训PPT.pptVIP

Acknowledgement Collaboration: Decai YU Carl Boone Max Lagally Ming-huang Huang Robert Blick Elizabath Lupton John Nairn Ji Zang Yu Zhang From Nanomechanical Science to Nanofabrication Technology: A New Route towards Nanotube Synthesis Feng Liu Department of Materials Science and Engineering University of Utah, Salt Lake City, UT A Hybrid Approach: Nanomechanical Architecture Growth Prinz et al., Physica E, 6, 828 (00); Schmidt and Eberl, Nature, 410, 168 (01) Patterning Release sacrificial top-down patterning + bottom-up self-assembly Nanoring Nanodrill Nanocoil Example: Si/SiGe Bi-layer Nanostructures Huang et al., Adv. Mat. 17, 2860 (05) (Huang) (Blick) (Blick) Estimation of Basic Dimension R t: bi-layer thickness; e: misfit strain Take e to be 1% – 10% For t = 1 – 100 nm R=10 – 1000 nm Fold into tube Fold into coil small WL0 Large W L0 W LL0 t d R0 Sin q c=W/L0 Design Principle: Nanotube vs. Nanocoil Geometric conditions for coiling: Phase Diagram for Tube vs. Coil Bending vs. Shearing n-th rotation: Tube (bending): Coil (shearing): Experimental Demonstration: elastic anisotropy (100) (110) Processing Condition: etching rate MPM Simulation Fast! Slow! Self-Bending of Si Nanofilm: The role of surface reconstruction [110] [001] (c) Zang, Huang, Liu, PRL 98, 146102 (07) Bending Curvature: Stoney Formula Derivation of a “Modified” Stoney Formula Z t Bending Curvature: Modified Stoney Formula Calibration of mechanochemical sensors Made of Si nanocantilevers Non-conventional Bending of Si/Ge Bi-layer Nanofilm [110] [001] Si Ge The Effect of Surface Stress Competition between surface stress and bulk misfit stress sts sbs sfilm 100 meV/?2 4tGe meV/?2 ~10 nm for SiGe, ~50 nm for Si/Si80Ge20 Critical thickness: Bending Curvature: Modified Timoshenko Formula Experimental Evidence Deneke et al., Semicond. Sci.Technol. 17, 1278 (02) Simulated Nanotubes R=74? R=46? R=78? Si SiGe GeSi Zang, Huang, Liu, PRL 98, 146102 (07) MD Simulations MD Simul