Study of gaseous interactions in carbon nanotube field-effect transistors through selective Si₃N₄ passivation

Carbon nanotube field-effect transistors with Si₃N₄ passivated source and drain contacts and exposed carbon nanotube channel show n-type characteristics in air. In contrast, by passivating only the source contact, a diode-like behavior with a maximum current rectification ratio of 4.6 × 10³ is observed. The rectifying characteristic vanishes in a vacuum but recovers once the devices are exposed to air. From our experiments, key parameters, such as critical gas pressure, adsorption energy of oxygen molecules and the contact barrier height modulation, can be obtained for studying the gaseous interaction in the carbon nanotube devices.