Optimization of Schottky barrier carbon nanotube field effect transistors

Carbon nanotube field-effect transistors (CNTFETs) have been studied in recent years as a potential alternative to CMOS devices, because of the capability of ballistic transport. CNTFETs can be fabricated with Ohmic or Schottky type contacts. We focus here on Schottky barrier CNTFETs which operate by modulating the transmission coefficient of carriers through the Schottky barriers at the interface between the metal and the carbon nanotube (CNT). The behavior of these devices has been studied by solving the coupled Schrödinger-Poisson equation system. In agreement with experimental results, simulations indicate the ambipolar behavior of these devices. However, the ambipolar behavior limits the performance of these devices in both on and off regimes. To suppress this effect a double gate structure is proposed. Simulations demonstrate that this structure exhibits improved device characteristics.