MRSEC Seminar

Selective Placement of Carbon Nanotubes for Electronics

Vincent Derycke

Laboratoire d'Electronique Moléculaire (LEM)
Service de Physique de l'Etat Condensé (SPEC)
CEA Saclay - France

Tuesday, December 4, 10 am

Cook Hall 2058

The high potential of carbon nanotubes as building blocks for nano-electronic devices is well established. But, if individual prototypes can display excellent performances, integration issues are critical, even for low density type of applications. Our laboratory has developed a wet self-assembly technique that allows the selective placement of nanotubes at predefined location on a substrate. It relies on the local functionalization of the substrate by a patterned molecular monolayer of an amine-terminated silane [1,2]. The method is versatile as it works for both single-wall and multi-wall nanotubes and for both individual nanotubes and networks of nanotubes. We use it as a generic technique to built FETs, optoelectronic devices and NEMs. After a brief description of the selective deposition technique, the presentation will focus on the devices issues and perspectives:

- Field effect transistors prepared in this way have very good performances and can be optimized by post fabrication chemical treatments [2]. We recently investigated the high frequency behavior of such nanotube transistors based on multiple nanotubes configurations and demonstrated current-gain cut-off frequencies (fT) of several GHz [3,4]. Such performances were also achieved on flexible substrates with remarkable performances upon bending.

- Further elaborating upon the chemical tailoring of the self-assembled CNT-FET devices, we have developed optically controlled CNT-FETs [5]. Upon photoexcitation, the device can be used as an optically driven current modulator or as a non volatile memory element working on an 'optical write / electrical erase' basis. In such a device, the nanotube is shown to act as a very sensitive probe to study the charge distribution and dynamics in polymer films.

- Finally, nano-electromechanical systems (NEMS) based on multiwall nanotubes can also be assembled with this technique. An example of efficient electro-mechanical switch based on an individual and partially suspended nanotube is reported [6]. Further development of nanotube NEMS requires precise simulations and experimental validations of the basic nanotube electro-mechanical properties. Our recent results on this topic [7] will be briefly presented.

[1] K.H. Choi et al, Surf. Sci. 462, 195 (2000).
[2] Auvray et al, Nano Lett. 5, 451 (2005).
[3] Bethoux et al, Elect. Dev. Lett. 27, 681 (2006).
[4] Le Louarn et al, Appl. Phys. Lett. 90, 233108 (2007).
[5] Borghetti et al, Adv. Mater. accepted (2006).
[6] Dujardin et al, Appl. Phys. Lett. 87, 193107 (2005).
[7] Lefèvre et al, Phys. Rev. Lett. 95, 185504 (2005).

Host: Professor Mark Hersam, MSE