Since their discovery, CNTs (Carbon Nanotubes) have fascinated many researchers due to their unprecedented electrical, optical, thermal and mechanical properties and their chemical sensitivity. These tubes are considered a promising component of future electronics. Recently, a complete computer based on CNT circuits has been demonstrated, and in the future they may be able to replace the silicon chip as the building block of electronics.
One of the biggest challenges on the way to the implementation of CNTs involves the need to produce them in specific locations on a smooth substrate, in conditions that will lead to the formation of a circuit around them. An article published in the journal Nature Communications presents a breakthrough in this regard, achieved in the laboratory of Prof. Yuval Yaish of the Viterbi Faculty of Electrical Engineering and the Zisapel Nanoelectronics Center at Technion. The technology developed by Prof. Yaish creates the said conditions and moreover, also makes it possible to study the dynamic properties of CNTs, including acceleration, resonance (vibration) and the transition from softness to hardness.
Due to the nanometer size of the CNTs (100,000 times smaller than the thickness of a human hair) it is extremely difficult to find or locate them at specific locations. Together with graduate student Gilad Zeevi and doctoral student Michael Shlafman, Prof. Yaish developed a simple, rapid, non-invasive, and scalable technique that enables optical imaging of CNTs. Instead of relying on the CNT chemical properties to bind marker molecules, the researchers relied on the fact that the CNT is both a chemical and physical defect on the otherwise flat and uniform surface. It can serve as a seed for the nucleation and growth of small size, optically visible, nano-crystals, which can be seen and studied using a conventional optical microscope (as opposed to CNTs, which are too small). As the CNT surface is not used to bind the molecules, they can be removed completely after imaging, leaving the surface intact. Thus the CNT’s electrical and mechanical properties are preserved.
“The integrated circuit, the chip, is the biggest breakthrough in electronics so far,” explains Prof. Yaish, “and we believe that the method we developed will serve as an applicable platform for the integration of nano-electronics with silicon technologies, and possibility even the replacement of these technologies in molecular electronics. The CNT is an amazing and very strong building block with remarkable electrical, mechanical and optical properties. Some of them are conductors and some are semiconductors, and therefore they are considered a future replacement for silicon. The unique infrastructures available at the Technion clean room facilities within the microelectronics center headed by Prof. Nir Tessler enable us not only to demonstrate this principle but also to produce world-class devices.”
According to Prof. Yaish, existing methods for the production of CNT are very slow and costly and result in a non-precision product and, in general, cannot be implemented in industry. “Our approach is the opposite of the norm. We grow the CNTs directly, and with the aid of the organic crystals that coat the CNTs we can see them under a microscope very quickly. Then image identification software finds the precise location of the CNTs, automatically designs the optimal electrical circuit and produces the device (transistor). This is the strategy. The goal is the integration of CNTs in an integrated circuit of miniaturized electronic components, mainly transistors, on a single chip (VLSI), which could, as stated, replace silicon electronics.”
Prof. Yuval Yaish earned his B.Sc. (cum laude) and M.Sc. (cum laude) in Physics from Tel Aviv University. He earned his Ph.D. – in Experimental Physics of Condensed Matter – at the Technion, under Prof. Uri Sivan. He did his postdoc in molecular electronics at Cornell University in the US.