Graphene edges modulate field-emission performance of graphenated carbon nanotubes

In this work, vertically aligned graphenated carbon nanotubes (g-CNTs) were synthesized by a single-step microwave plasma-enhanced chemical vapor deposition process on Si substrates. The density of graphene foliates was tuned by controlling the growth time at 1050 °C and subsequently assessed through nanotube diameter measurements and Raman spectroscopy parameters. Increasing graphene foliate density led to a systematic increase in apparent tube diameter, indicating progressive graphene growth along the nanotube sidewalls. Field-emission performance was evaluated using complementary statistical stability metrics, including variance, Allan deviation, and frequency-domain noise analysis, and correlated with the structural features of the emitters. Compared to bare CNTs, g-CNTs exhibited improved current stability under constant bias. Stable emission was sustained with mean current levels in the microampere range, while the average emission current decreased and the turn-on field increased systematically with increasing foliate density. The results indicate that graphenation modifies both the geometric and electrical characteristics of CNT emitters, leading to reduced current fluctuations and improved current stability at the expense of higher emission thresholds. These findings demonstrate an intrinsic trade-off between emission efficiency and current stability and highlight graphene foliate density as a key morphological parameter for tuning field-emission behavior in graphenated CNT cold cathodes.

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Author Jeffrey Glass Pierre R. Lamond Department of Electrical and Computer Engin ...

Author Jason Amsden Pierre R. Lamond Department of Electrical and Computer Engin ...

Author Charles Parker