Effects of Parylene Coating on Electron Transport in Pristine Suspended Carbon Nanotube Field-Effect-Transistors

Carbon nanotube (CNT) field effect transistors (FETs) are anticipated to provide a viable alternative to silicon as CMOS technology begins to reach ultimate scaling lengths. With high carrier mobilities, current density, and tunable bandgaps, CNTs can allow for the growth of the transistor industry beyond traditional materials. However, these nanotubes are sensitive to their surroundings and require a protective passivation layer to isolate them from contamination by their external environment. Thin parylene films have been shown to be a practical passivation layer for CNT devices as a flexible, chemically inert, high dielectric strength, pinhole-free material. In this paper, we perform electrical characterization of single suspended CNT FETs before and after passivation with parylene-C thin-film deposition. Analysis shows moderate changes in the threshold voltage, subthreshold slope, and ON/OFF ratio with parylene passivation, indicating minimal effect on the CNT FET overall performance.