Nanoscale Interfacial Band Bending for Enhanced Cold Field Emission in GCN−ZnO Hybrids: Experimental and First-Principles Validation

Abstract In this work, we explore the enhancement of cold field emission (CFE) characteristics in the hybrid zinc oxide (ZnO) and graphitic carbon nitride (GCN) hybrid structure, aiming to optimize their performance in vacuum microelectronics applications. ZnO, GCN, and GCN-ZnO nanostructures were synthesized via wet chemical synthesis and hydrothermal process and were characterized by using different techniques. The field emission scanning electron microscope and transmission electron microscopy analyses revealed the morphology and formation of interconnected ZnO nanorods anchored over sheet-like GCN structures. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopic studies analyzed the chemical bond and elemental composition in the sample. To further understand the electronic behavior of the individual materials, density functional theory calculations based on the GGA-PBE approximation were performed to analyze the band structure and density of states. Furthermore, ANSYS Maxwell simulation confirmed an enhanced local electric field distribution and electron accumulation at the hetero-interface favorable for cold emission properties. The hybrid sample exhibited significantly improved CFE performance with a low turn-on field of 4.1 V/μm and a high emission current density of 138.8 μA/cm2 compared to the individual materials. The enhanced emission characteristics are mainly attributed to the increased number of active emission sites, efficient interfacial charge transfer, and reduced potential barrier caused by band bending at the GCN-ZnO interface.