Influence of nucleation layer on the conductivity of diamond films synthesized by bias-enhanced microwave plasma CVD process

• Main Authors: Hsin-Tse Chang, 張信澤
• Other Authors: I-Nan Lin
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/77603278460589372884

碩士 === 淡江大學 === 物理學系碩士班 === 103 === Diamond films possess high hardness, god tribological properties, superb electron field (EFE) properties and high thermal conductivity. They have great potential for applications such as electron field emitters, microelectromechanical devices, biomaterials, surface acoustic wave devices. Diamond films can be microcrystalline (MCD), nanocrystalline (NCD) an ultrananocrystalline (UNCD), among which the UNCD films exhibit the most smooth surface, the best conductivity and moreover, the best EFE properties. In first part of research, we investigated the effect of different substrate materials on the growth behavior of UNCD films. We grew diamond films on (i) bare-Si, (ii) UNCD coated Si (non-biased) and (iii) UNCD/SI (bias grown) using CH4(6%)/N2 plasma, without bias or under bias. In the second part of research, based on the optimum parameters developed in the first part of research, we bias-enhanced grew diamond films on UNCD/Si (without bias) for 10-60 min, examine the development of microstructure of the UNCD films and the related EFE properties. We observed that the CH4/N2 beg-grown diamond films on UNCD (no bias)?Si substrates exhibit superior conductivity/EFE properties to other kind of diamond films. We examined the granular structure of thus obtained UNCD films using TEM and observed that these films contain needle-like diamond grains encased with nano-graphitic layers. The size of needle-like diamond grains is 5 nm in diameters and ~150 nm in length, which has better aspect ratio than conventional diamond films with wire-like granules structure. The incorporation of 0.1%H2 resulted in needle-like diamond grains of smaller aspect ratio, which degraded the conductivity/EFE properties of the UNCD films.