Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 11: Focus Session: Sensoric Micro and Nano-systems I

DS 11.8: Talk

Tuesday, April 1, 2014, 12:00–12:15, CHE 89

Adjustment of carbon nanotube properties for sensor applications using Pd adatoms: An ab-initio study — •Florian Fuchs¹, Christian Wagner¹, Andreas Zienert¹, and Jörg Schuster² — ¹Center for Microtechnologies, Technische Universität Chemnitz, Chemnitz, Germany — ²Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz, Germany

Carbon nanotubes (CNTs) are, thanks to their extraordinary electromechanical properties, suitable for novel sensing devices such as acceleration sensors. For such applications, CNTs with small band gaps are favored. Since type selection of CNTs is still a challenge, methods are required to tune the band gaps in situ. We suggest submonolayer metal coating as a promising approach.

By using density functional theory, we investigate the influence of Pd adatoms on the surface of a semiconducting (8,4) CNT. We show that the adatoms strongly influence the electronic properties and that the band gap can be reduced. This effect can be increased further by using higher amounts of Pd adatoms. When the adatoms finally create a closed chain along the CNT, the band gap is reduced to the desired working range of possible sensor devices. Straining the system in uniaxial direction shows that the sensibility of the band gap and therefore the suitability for strain sensors is conserved. We also vary the position of a single adatom on the CNT surface in order to judge the stability of the adsorption. The resulting energy landscape shows a valley along the tube. Within that valley, energy barriers are small enough to permit thermally activated motion of the adatom.