Improved Field Electron Emission Properties of Phosphorus and Nitrogen Co-Doped Nanocrystalline Diamond Films

Abstract

Nanocrystalline diamond (NCD) field emitters have attracted significant interest for vacuum microelectronics applications. This work presents an approach to enhance the field electron emission (FEE) properties of NCD films by co-doping phosphorus (P) and nitrogen (N) using microwave plasma-enhanced chemical vapor deposition. While the methane (CH4) and P concentrations are kept constant, the N2 concentration is varied from 0.2% to 2% and supplemented by H2. The composition of the gas mixture is tracked in situ by optical emission spectroscopy. Scanning electron microscopy, atomic force microscopy (AFM), transmission electron microscopy, and Raman spectroscopy are used to provide evidence of the changes in crystal morphology, surface roughness, microstructure, and crystalline quality of the different NCD samples. The FEE results display that the 2% N2 concentration sample had the best FEE properties, viz. the lowest turn-on field value of 14.3 V/µm and the highest current value of 2.7 µA at an applied field of 73.0 V/µm. Conductive AFM studies reveal that the 2% N2 concentration NCD sample showed more emission sites, both from the diamond grains and the grain boundaries surrounding them. While phosphorus doping increased the electrical conductivity of the diamond grains, the incorporation of N2 during growth facilitated the formation of nano-graphitic grain boundary phases that provide conducting pathways for the electrons, thereby improving the FEE properties for the 2% N2 concentrated NCD films.

An innovative GC-MS, NMR and ESR combined, gas-phase investigation during chemical vapor deposition of silicon oxynitrides films from tris(dimethylsilyl)amine

“…23 More recent implementations involve in situ Raman spectroscopy during thermal decomposition of a tungsten imido complex by aerosol-assisted (AA)CVD, 24 or in situ optical emission spectroscopy during microwave plasma-enhanced chemical vapor deposition of phosphorus (P) and nitrogen (N) co-doped nanocrystalline diamond. 25 Focusing on analogous studies of CVD processes involving silicon-containing precursors, the majority of the reported 6 literature concerns the binary systems SiC, SiO2 or Si3N4 from chlorosilanes, silanes or TEOS. Among them, Zhang et al 26 used GC-MS for the characterization of the gas phase during the deposition of SiC from methyltrichlorosilane in the presence of H2, identifying HCl and SiCl4 molecules as by-products.…”

Effect of oxygen on regulation of properties of moderately boron-doped diamond films

“…The co-doping of boron and oxygen has been widely investigated by many groups. [13][14][15] For example, Issaoui et al [16] have studied the effect of oxygen on the heavily boron-doped diamond and shown that the obtained films exhibit high crystalline quality with adding a large amount of oxygen in gas phase. However, most of the prior literature focuses on the effect of oxygen on the properties (such as crystalline quality, [17,18] growth rate, [18,19] and electrical property [17,19] ) in heavily boron-doped diamond.…”

Nitrogen-Incorporated Boron-Doped Nanocrystalline Diamond Nanowires for Microplasma Illumination

“…Using suitable dopants and impurities, it is practicable to synthesize electrically conducting diamond films and also the conductivity can be tailored related to the application requirement. 12, 13 Diamond films with micron-sized grains are designated as microcrystalline diamond (MCD) films, which possess high resistivity. 14 By incorporation of nitrogen in CH 4 /H 2 plasma, the grain size reduces from micron to nanosize, ensuing the formation of nanocrystalline diamond (NCD) films.…”

“…Along with the abovementioned properties, diamond films should be electrically conducting to be an efficient cathode in microplasma devices. Using suitable dopants and impurities, it is practicable to synthesize electrically conducting diamond films and also the conductivity can be tailored related to the application requirement. , …”