Device characterization of carbon nanotubes field emitters in diode and triode configurations

Device characteristics of thermal CVD grown carbon nanotubes (CNTs) field emitters in diode and triode configurations are reported. The CNT cathode configured as field emission diode exhibited a low turn-on field of ∼3.0 V/μm, high emission current of ∼35 mA at ∼5.0 V/μm, and excellent current stability. Large signal model (dc) and small signal model (ac) of the field emission diode were also investigated. The CNT triode was achieved by integrating a TEM grid (transmission electron microscope specimen holder) as the gate electrode to the CNT cathode, with no further micro-fabrication processes needed. The CNT triode displayed gate-controlled current modulation behavior with distinct cutoff, linear and saturation regions. The triode has a gate turn-on field of ∼5.4 V/μm despite a large cathode-gate spacing of ∼120 μm. The field emission data established the basic transistor characteristics of CNT emitters in a triode amplifier configuration with good gain. The detailed dc characteristics and transistor ac parameters such as transconductance, amplification factor, and anode resistance for the CNT triode were investigated and modeled.