Nanomechanical memory Victor Zhirnov Emerging Memory Workshop Emerging Research Devices Meeting April 2, 2008

2 CNT cross-bar memory Expectations: n=10 12 bits/cm 2, f=100 GHz Rueckes T. et al., SCIENCE 289 (5476): JUL Moving Atoms u Each memory element is based on suspended crossed carbon nanotubes. u Cross-bar array of CNT forms mechanically bi-stable, electrostatically-switchable device elements at each cross point. u The memory state is read out as the junction resistance. Concept

3 Scaling Law in CNT Electromechanical Devices R. Lefèvre, 1 M. F. Goffman, 1 V. Derycke, 1 C. Miko, 2 L. Forró, 2 J. P. Bourgoin, 1 P. Hesto 3 Phys. Rev. Lett. 95, (2005) Young’s modulus Correction factor (1.21…1.45) L=700 nm, D=10 nm L=480 nm, D=10 nm L=700 nm, D=10 nm 500 nm H=230 nm =1.456 = Laboratoire d'Electronique Moléculaire, CEA-DSM SPEC, CEA Saclay, France 2 EPFL, CH-1015, Lausanne, Switzerland 3 Institut d'Electronique Fondamentale, CNRS, Université Paris 11, France

4 Calculation of pull-in voltages for carbon- nanotube-based nanoelectromechanical switch M. Dequesnes, S. V. Rotkin, and N. R. Aluru Nanotechnology 13 (2002)

5 Pull-in voltage increases with size scaling 10 nm 1 nm Dequesnes Lefèvre H=1 nm

6 u [A] J. W. Ward, M. Meinhold, B. M. Segal, J. Berg, R. Sen, R. Sivarajan, D. K. Brock, and T. Rueckes, “A non-volatile nanoelectromechanical memory element utilizing a fabric of carbon nanotubes”, Non-Volatile Memory Technology Symposium, Nov. 2004, pp u [B] T. Rueckes et al., Carbon nanotube-Based Nonvolatile Random Access Memory for Molecular Computing, SCIENCE 289 (2000): u [C] u [D] The projections for WRITE voltage and WRITE energy depend on the length of nano-electro-mechanical element. For very small length, the operating voltage might be too high for practical use, as follows from theoretical analysis in: M. Dequesnes et al, “Calculation of pull-in voltages for carbon-nanotube-based nanoelectromechanical switch”, Nanotechnology 13 (2002) 120; R. Lefevre et al., “Scaling Law in Carbon Nanotube Electromechanical Devices”, Phys. Rev. Lett. 95 (2005)

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8 CNT cross-bar memory Expectations: n=10 12 bits/cm 2, f=100 GHz Rueckes T. et al., SCIENCE 289 (5476): JUL Moving Atoms u Each memory element is based on suspended crossed carbon nanotubes. u Cross-bar array of CNT forms mechanically bi-stable, electrostatically-switchable device elements at each cross point. u The memory state is read out as the junction resistance. Concept

9 Nanoscale memory cell based on a nanoelectromechanical switched capacitor Amaratunga’s group, Cambridge Univ. Nature Nanotechnology 3 (2008) 26