Carbon Nanotubes Circuits Made Easy - Optical Imaging of CNTs


  Y. E. Yaish  ,  G. Zeevi  ,  M. Shlafman  ,  T. Tabachnik  ,  Z. Rogachevsky  ,  S. Maliniak  ,  I. Goldstein  ,  S. Shlafman  ,  N. Gordon  ,  G. Alchanati  ,  Y. Moshe  ,  E. M. Hajaj  ,  H. Nir  ,  Y. Milyutin  ,  T. Y. Izraeli  ,  A. Razin  ,  O. Shtempluck  ,  V. Kotchtakov  
Faculty of Electrical Engineering, Technion

Since their discovery carbon nanotubes (CNTs) have fascinated many researchers due to their unprecedented electrical, optical, thermal, and mechanical properties. Recently, a complete computer based on CNT circuits has been demonstrated. However, a major drawback in utilizing CNTs for practical applications is the difficulty in positioning or growing them at speciļ¬c locations or in locating them on the substrate such that the circuit can be built around them.

Here we present a simple, rapid, non-invasive, and scalable technique that enables optical imaging of CNT. Instead of relying on the CNT chemical properties to bind marker molecules we rely on the fact that the CNT is both chemical and physical defect on the otherwise flat and uniform surface. Namely, it may serve as a seed for nucleation and growth of small size, optically visible, nano-crystals. As the CNT surface is not used to bind the molecules they can be removed completely leaving the surface intact and thus the CNT electrical and mechanical properties are preserved. By choosing a small molecule with suitable vapor pressure it is self-removed via sublimation off the CNT surface. The successful and robust optical imaging allowed us to develop a dedicated image processing algorithm through which we are able to demonstrate a fully automated circuit design resulting in field effects transistors and inverters. Moreover, we demonstrate that this imaging method allows not only to locate CNTs but also, as in the case of suspended ones, to study their mechanical motion including modes shape, resonance frequencies, dissipation phenomena, and nonlinear behavior.