Chemical Vapor Deposition

Review: The growth, characteristics, and applications of nanocrystalline and ultrananocrystalline diamond thin films with thicknesses from 20 nm to less than 5 microns are reviewed. These materials contain between 95% and >99.9% diamond crystallites with the balance made up from other forms of carbon.

Review: Nanocrystalline B-doped diamond films are grown by the PE-CVD method and the influence of doping and substrate treatments on layer composition and the diamond film topology are discussed. Starting from the randomness of boron sublattice and experimental transport data, we develop a theory of unconventional superconductivity in this material. We also show that point contacts between grains play a role of weak links affecting superconductivity and other quantum transport phenomena.

Full Paper: Ar/H₂/CH₄ pulsed microwave discharges used for nanocrystalline diamond film deposition are investigated. Emission and broadband absorption spectroscopy techniques are carried out in order to reach the gas temperature and the total density of C₂ molecule. Time-resolved fast imaging is performed in order to observe the plasma ignition and expansion during the microwave pulse.

Full Paper: Nanocrystalline diamond (NCD) thin films were grown on silicon and glass substrates at low substrate temperature. Development of nano-sized diamond crystals and their clusters, and formation of continuous layer is investigated by AFM, SEM and XPS measurements, as a function of process time. The found dependences indicate that 2D growth takes a place at low substrate temperatures. Grown NCD films are optically transparent in a wide spectral range.

Full Paper: Deposition of thin nanocrystalline diamond films requires a high control of the nucleation stage. The successive steps of the Bias Enhanced Nucleation process have been in situ studied on Si (100) and 3C-SiC (100). The formation of a thin SiC layer during the Plasma Exposure for Parameters Stabilization step leads us to study the plasma / surface interactions on 3C-SiC (100) surfaces. The C-terminated 3C-SiC (100) demonstrates a large inertia. Surface analysis reveals low damages after BEN on it.

Full Paper: Recent studies of the incorporation of hydrogen and its bonding configuration in diamond films composed of diamond grains of varying size are reviewed. Polycrystalline-diamond films are deposited by hot filament (HF), microwave (MW) and direct current glow discharge (DCGD)CVD. The size of the diamond grains which constitute the films varies in by hundreds of nanometers in the case of HFCVD, tens of nanometers in the case of MWCVD, and a few nanometers in the case of DCGDCVD (ultra nanocrystalline diamond). Raman spectroscopy, secondary ion mass spectroscopy, and high-resolution electron energy loss spectroscopy are applied to investigate the hydrogen trapping in the films. The hydrogen retention of the diamond films increases with decreasing grain size, indicating the likelihood that hydrogen is bonded and trapped in grain boundaries, as well as on the internal grain surfaces.

Full Paper: The sticking and etch coefficients of various hydrocarbon species that may affect the growth of ultrananocrystalline and nanocrystalline diamond ((U)NCD) films are calculated by means of molecular dynamics simulations. The simulations are carried out for clean and hydrogenated diamond (100)2 × 1 and (111)1 × 1 surfaces at two temperatures. A temperature-dependent ratio of diamond (100) and (111) growth is predicted. Conclusions about the most important species for (U)NCD growth are drawn.

Full Paper: The effect of substitutional N on CH₃ adsorption and H abstraction have been calculated for both (111) and (100) surfaces. When N is positioned within the second carbon layer, the CH₃ adsorption is energetically disfavoured whilst the CH₂ formation is favoured. With N next to the reactive site, the finally formed CH₂ is observed to form sp² surface carbons which might be responsible for surface degradation at high N concentration.

Full Paper: The morphology of ultra-nanocrystalline diamond films has been modelled by a pure geometrical approach. Diamond spheres with a fixed radius are added randomly spread on a smooth substrate surface covered with diamond seeds in varied primary nucleation density. The secondary nucleation rate and the nucleation density on the bare substrate define the distribution of diamond spheres during each cycle. This simple geometrical model leads to good comparison with published experimental data: low primary nucleation densities yield to the growth of separated diamond islands with a rough surface, the smoothest films are obtained with the highest primary nucleation densities.

Full Paper: Nanodiamond and carbon nanotube–diamond nanocomposite films were synthesized on silicon substrates, discharging hydrogen based gas mixture, using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). Prior to deposition, the silicon substrate was treated using M(NO₃)₃/Mg(NO₃)₂.6H₂O (M=Co, Fe, Ni). The growth mechanisms for ND and CNTD nanocomposite were discussed.

Full Paper: Recently, the production of nanodiamond-coated bundles of single walled nanotubes (SWNT) by a CVD technique, using carbon nanoparticles as carbon source material, has been demonstrated. The present research work has been focussed on the production of nanotubes only partially coated by diamond. The evolution of the nanodiamond/nanotube hybrid structure has been investigated by performing cathodoluminescence, Raman and RHEED measurements.

Full Paper: By using a high-temperature (>1100°C) microwave plasma chemical vapor deposition technique, a large quantity of hexagonal single crystalline diamond nanoplatelets can be obtained. This paper describes the influence of deposition conditions and various sample placements in an MPCVD reactor on the growth behaviors of diamond nanoplatelets. Transmission electron microscopy characterization reveals that the lateral growth of platelets closely relates to ridge-and-trough side face structure of twinned platelets and intense plasma reaction.