Consistently low subthreshold swing in carbon nanotube transistors using lanthanum oxide

While a few singular reports have demonstrated carbon nanotube (CNT) transistors with subthreshold swings (SS) close to the theoretical limit (60 mV/decade), the majority of devices have more than double the target swing. Here, we show that a low temperature lanthanum oxide dielectric is able to yield a consistently and reproducibly low SS, with an average of 73 mV/decade and a low of 63 mV/decade. This LaOx film is characterized using medium energy ion scattering and shown to be scalable down to 3.5 nm with minimal leakage and a variation in swing of only 613%. With interface traps playing a dominant role in the switching behavior of CNT transistors, these results reveal the existence of dielectrics with more favorable interfacial characteristics for nanotubes that yield low SS devices. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4774000]