Nanostair Formation and Field Emission Enhancement on High Dose N-Ion-Implanted Ultrananocrystalline Diamond Pyramid Tips

Abstract

We herein report high dose nitrogen (N) ion implantation induced nanostructural modifications and enhanced electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) pyramid tips. Transmission electron microscopy investigations indicate nanostair type surface formation on the pyramid tips. Evidence of complex nanostructural changes due to ion implantation are found, such as, graphitic or amorphous type transition, volume expansion (about 0.56 μm³), and nanostair type surface formation. The nanostructural modifications possibly enhanced the grain boundary incorporation of N and the electron transport through a transfer doping mechanism, which in turn improved the EFE properties of the ion-implanted pyramid tips. In particular upon N ion implantation the turn-on field is found to reduce from 3.6 V/μm (for unimplanted tips) to 2.8 V/μm and the current density is increased from 0.1 mA/cm² (unimplanted tips) to 5.4 mA/cm² at an applied field of 12.5 V/μm.