Diamond-gold nanohybrids – an enhanced cathode material for field electron emitter applications

Abstract

This work aims to review the enhancement of electrical conductivity and field electron emission (FEE) properties of ultrananocrystalline diamond (UNCD) films as a function of gold ion implantation content. Au has been employed in UNCD films as an implanted species as well as an interlayer between diamond film and substrate. In the initial part of the review UNCD films are briefly introduced. The focus is on their FEE properties and multiple strategies employed for enhancing these properties using ion-implantation with the goal to obtain a better cathode material. A comparison of the characteristics of the UNCD films implanted with Au and other species after studying the modification of the microstructure and emission properties of the Au-implanted UNCD films is then provided. Subsequently, the use of a thin Au coating on silicon substrates covered by UNCD or hybrid granular structured diamond films is discussed. The Si diffusion through the Au-Si eutectic interface results in a SiC layer. This facilitates the nucleation of diamond clusters, thereby suppressing the development of the carbon layer which is amorphous and electrically resistive, resulting in improved FEE characteristics. Finally, in the third and final part, the combined effects of Au-ion implantation (including multi-energy Au ion implantation) and Au-interlayer is discussed. Based on the obtained results, the catalytic activity of gold for improving the electrical conductivity and the FEE properties of diamond films is highlighted.