Toward Linearity in Schottky Barrier CNTFETs

Carbon nanotube field-effect transistors are expected to be beneficial for analog high-frequency applications due to, among others, their inherent linearity and, thus, very low signal distortion. Achieving this linearity has so far been assumed to depend on meeting the following conditions: Ballistic single-subband transport, ohmic contacts, and quantum capacitance limited operation. However, these conditions are very difficult to meet in realistic devices and circuit applications. It is shown in this paper that high linearity is also possible under significantly relaxed and, in particular, more practical conditions. This paves the way toward the exploration of linearity in realistic devices suffering from carrier scattering in the channel and with Schottky-like contacts, as well as thicker and lower-κ gate oxides, which do not allow operation in the quantum capacitance limit. This study is based on results obtained with a Boltzmann transport equCarbon nanotube field-effect transistors are expected to be beneficial for analog high-frequency applications due to, among others, their inherent linearity and, thus, very low signal distortion. Achieving this linearity has so far been assumed to depend on meeting the following conditions: Ballistic single-subband transport, ohmic contacts, and quantum capacitance limited operation1. However, these conditions are very difficult to meet in realistic devices and circuit applications. It is shown in this paper that high linearity is also possible under significantly relaxed and, in particular, more practical conditions. This paves the way toward the exploration of linearity in realistic devices suffering from carrier scattering in the channel and with Schottky-like contacts, as well as thicker and lower-κ gate oxides, which do not allow operation in the quantum capacitance limit. This study is based on results obtained with a Boltzmann transport equation solver that includes tunneling through potential barriers.ation solver that includes tunneling through potential barriers.