Study of field emission properties of pure graphene-CNT heterostructures connected via seamless interface

Vertically aligned carbon nanotubes (CNTs) have proven to be one of the best materials for use as an efficient field emitter. To further improve their efficiency as well as long-term use in practical devices, it is necessary to reduce the quantum resistance originating from the interface between electrode and emitters and the entanglement of the CNTs in a bundle texture. Thus, the incorporation of graphene at the bottom of CNT bundles via a seamless carbonaceous interface can easily solve this bottleneck. In this work we have demonstrated for the first time, growth and field emission properties of pure seamless graphene-CNT heterostructures and pure seamless graphene-vertically patterned oriented CNTs heterostructures (SGVCNTs) on Si/SiO₂ substrates in contrast to the bare CNT mats and few-layer graphene structures without using any tedious post transfer processes. It was observed that seamless SGVCNTs show better field emission performance in terms of higher current density (236 mA cm^-2), lowered turn-on field (0.45 V μm^-1) and threshold field (1.931 V μm^-1 @100 mA cm^-2), and improved field enhancement factor (β ∼ 41 315) which is improved ∼4 fold when compared to a bare CNT mat. The significant improvement of the field emission performance of SGVCNTs is mainly attributed to the low resistive seamless C-C covalent carbonaceous interface, the higher number of emitter sites and patterned vertical orientation that leads to long-term stability of the field emitter with minimal loss up to 32 h. This finding could provide an important solution for carbonaceous material based field emitters for real phase device applications.