Carbon Nanotubes as Schottky Barrier Transistors

Field-effect transistors (FETs) made with carbon nanotubes have many attractive features, and are being widely studied as a potential nanoscale successor to silicon FETs. Remarkably, we found that nanotube FETs generally operate by a completely different principle than ordinary Si FETs. Rather than modulate the conductance of the channel, the gate field acts to modulate the tunneling conductance of a Schottky barrier at the contact [1]. As a result, the device performance is determined by completely different factors than in familiar FETs [2-4]. In particular, the nanoscale electric field distribution near the contacts plays a crucial role. As a result, the geometry and workfunction of the contact become as important as more familiar factors like gate-oxide thickness. In addition, there are fundamental differences in the role of Fermi-level pinning at the metal-nanotube contact, compared to ordinary semiconductor interfaces [5]. \\ 1. S. Heinze, J. Tersoff, R. Martel, V. Derycke, J. Appenzeller, and Ph. Avouris, Phys. Rev. Lett. 89, 106801 (2002). \\ 2. S. Heinze, M. Radosavljevic, J. Tersoff, and Ph. Avouris, Phys. Rev. B 68, 235418 (2003). \\ 3. M. Radosavljevic, S. Heinze, J. Tersoff, and Ph. Avouris, Appl. Phys. Lett. 83, 2435 (2003). \\ 4. S. Heinze, J. Tersoff, and Ph. Avouris, Appl. Phys. Lett. 83, 5038 (2003). \\ 5. F. Leonard and J. Tersoff, Phys. Rev. Lett. 84, 4693 (2000).