ABSTRACT
Ion-beam-induced deposition (IBID) and electron-beam-induced deposition (EBID) with tungsten (W) are evaluated for engineering electrical contacts with carbon nanofibers (CNFs). While a different tungsten-containing precursor gas is utilized for each technique, the resulting tungsten deposits result in significant contact resistance reduction. The performance of CNF devices with W contacts is examined and conduction across these contacts is analyzed. IBID-W, while yielding lower contact resistance than EBID-W, can be problematic in the presence of on-chip semiconducting devices, whereas EBID-W provides substantial contact resistance reduction that can be further improved by current stressing. Significant differences between IBID-W and EBID-W are observed at the electrode contact interfaces using high-resolution transmission electron microscopy. These differences are consistent with the observed electrical behaviors of their respective test devices.
ABSTRACT
We demonstrated that the diameter and the density of carbon nanotubes (CNTs) which had a close relation to electric-field-screening effect could be easily changed by the control of catalytic Ni thickness combined with NH3 plasma pretreatment. Since the diameter and the density of CNTs had a tremendous impact on the field-emission characteristics, optimized thickness of catalyst and application of plasma pretreatment greatly improved the emission efficiency of CNTs. In the field emission test using diode-type configuration, well-dispersed thinner CNTs exhibited lower turn-on voltage and higher field enhancement factor than the densely-packed CNTs. A CNT film grown using a plasma-pretreated 25 angstroms-thick Ni catalyst showed excellent field emission characteristics with a very low turn-on field of 1.1 V/microm @ 10 microA/cm2 and a high emission current density of 1.9 mA/cm2 @ 4.0 V/microm, respectively.
