Temperature-Dependent Defect Modulation and Corrugated Ni–Mo Bimetallic Micro-Pyramids for Enhanced Graphene Field Emission

Developing high-performance and practical graphene-based field emission materials remains a significant challenge, primarily due to the difficulty in balancing the density of emission sites with structural stability. Herein, we designed a Ni–Mo bimetallic interlayer to achieve the in situ growth of multilayer graphene (MLG) on microscale silicon tip arrays via radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD). This approach leverages MEMS-fabricated microtip arrays to provide strong field enhancement. Meanwhile, the Ni–Mo bimetallic interlayer induces periodically corrugated MLG through the Kirkendall effect. To clarify the underlying mechanism, we developed an MLG growth model to describe the chemical reactions during deposition. We also derived a texture evolution model based on the Kirkendall effect. Furthermore, the defect density of the MLG can be precisely controlled by adjusting the growth temperature. Our results show that the composite cathode achieves optimal field emission performance when ID/IG in the Raman spectrum is approximately 0.33. The composite cathode MLG/Ni–Mo/Si-tip exhibited low turn-on field (E0 = 2.72 V/μm), a high current density (Jmax = 25 mA/cm2 at 5.78 V/μm), a large field enhancement factor (β) of ∼2121 at a growth temperature of 750 °C. In comparison, the MLG/Ni/Si-tip group exhibits an optimal turn-on field of 3.93 V/μm. These results demonstrate that the proposed design effectively integrates the field-enhancement advantages of microtip cathodes with the superior emission capabilities of two-dimensional (2D) graphene. This approach provides a meaningful synergistic strategy, combining structural and material optimizations to improve graphene-based field emitters.