Growth of n-type 3C-SiC nanoneedles on carbon fabric: Toward extremely flexible field emission devices

Flexible field emission (FE) arrays have a wide range of applications in next generation low-cost, lightweight and wearable electronics, roll-up displays, and large-area circuits on curved objects, yet the growth of tapered, high-quality single-crystalline nanostructure-based emitters on flexible substrates with superior FE properties remains challenging and related work is limited. On the other hand, our recent studies have shown that silicon carbide (SiC) 1D nanostructures could meet nearly any stringent requirement for an ideal FE emitter. In this contribution, we report the growth of quasi-aligned, single-crystalline n-type doped (N-doped) 3C-SiC nanoneedles (3C-SiCNNs) on highly flexible carbon fabric via the catalyst assisted pyrolysis of polysilazane. The as-synthesized SiCNNs possess a tapered structure with tiny clear tips with sizes of several to tens of nanometers. The fabricated 3C-SiCNNs have extremely low emission turn-on fields (E_on) in the range of 0.5-1.6 V μm^-1 with an average of 1.1 V μm^-1, which is comparable to the lowest value ever reported for 1D nanostructure emitters that, however, are grown on rigid substrates. Specifically, our SiCNN arrays on carbon fabric are mechanically and electrically robust, and can withstand mechanical bending up to 500 times and still retain excellent FE performance with E_on of ∼1.1 V μm^-1. The field-enhancement factor has been calculated to be 6.5 × 10³. The superior FE properties can be attributed to the significant enhancements of the tapered unique morphology and N-doping of the SiCNNs. Calculations based on local density functional theory suggest that nitrogen dopants in the 3C-SiC nanostructure could favor a more localized impurity state near the conduction band edge, which improves the electron field emission. We strongly believe that the present work will provide a new insight into the fabrication of flexible field emission arrays with ultralow turn-on fields enhanced by both shape and doping.