Using an Au interlayer to enhance electron field emission properties of ultrananocrystalline diamond films

Abstract

We observe that an Au interlayer markedly enhances the electrical field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films on Si substrates. The EFE properties of UNCD/Au/Si films can be turned on at a lower field and attain a higher current density than in UNCD films grown on Si substrates without an Au interlayer. Transmission electron microscopy reveals that the Au interlayer induces the formation of SiC clusters, preventing the formation of a resistive amorphous carbon layer that nucleates the diamond clusters. This improves the diamond-to-substrate interfacial conductivity. Moreover, there is an abundant nano-graphite phase, which is presumably induced by the coalescence of nano-sized diamond clusters. The percolation of the nano-graphite clusters helps transport electrons, improving the conductivity of the UNCD films. We believe that the simultaneous increase in the conductivity of the UNCD-to-Si interface and the bulk of the UNCD films is the main factor enhancing electrical conductivity and EFE properties of the films.

Field electron emission enhancement in lithium implanted and annealed nitrogen-incorporated nanocrystalline diamond films

“…[1][2][3] The sp 2 -bonded carbon in the grain boundaries of NCD films is the genuine factor for the enhanced FEE properties of these films as compared with MCD films. 4,5 The non-diamond carbon is not conductive enough, restricting the FEE characteristics achievable for NCD films. Facilitating the formation of nanographitic phases in the grain boundaries due to nitrogen addition (>20%) in the CH 4 /Ar plasma can improve the electrical conductivity (EC) that enhances the FEE properties of diamond films.…”

High-Performance Electron Field Emitters and Microplasma Cathodes Based on Conductive Hybrid Granular Structured Diamond Materials

“…39,40 There have been great efforts in improving the EFE of UNCD films via the suppression of the appearance of an a-C phase present at the diamond−Si interface. 41,42 It has been reported that the turn-on field of diamond films can be lowered markedly due to the elimination of the a-C phase via the utilization of Au coating as interlayer. 41,42 However, it is a complicated process, as the thickness of the Au coating needs to be critically controlled.…”

Multienergy gold ion implantation for enhancing the field electron emission characteristics of heterogranular structured diamond films grown on Au-coated Si substrates

“…The process of Au and Cr deposition on Si and the pre-seeding process for the growth of diamond on these Au(Si) substrates are described in detail elsewhere. 15,16 The UNCD films were first deposited using microwave plasma enhanced chemical vapor deposition (MPECVD) system in Ar(99%)/CH 4 (1%) plasma under 1200 W and 120 Torr for 90 min. The plane view scanning electron microscopy (SEM; Jeol 6500) image shown in Fig.…”

“…Hence, the formation of Au(Si) eutectic layer eliminates the origin of the a-C phase in the vicinity of interface, which lowers the resistivity of the interface layer. 15,16 Seemingly, the SiC was formed due to the interaction of Si and C species, i.e., the Si species have diffused through the Au(Si) eutectic layer to react with the carbon promptly, forming SiC. The SiC can enhance the efficiency for the nucleation of diamond.…”

“…The SiC can enhance the efficiency for the nucleation of diamond. 16 On the other hand, region I of the SIMS studies (cf. Fig.…”