Homogeneous reactions of hydrocarbons, silane, and chlorosilanes in radiofrequency plasmas at low pressures

The ion-molecule and radical-molecule mechanisms are responsible for the dissociation of hydrocarbon, silane, and chlorosilane monomers and the formation of polymerized species, respectively, in an RF plasma discharge. In a plasma containing a mixture of monomer and argon the rate-determining step for both dissociation and polymerization is governed by an ion-molecule type of interaction. Adding hydrogen or ammonia to the monomer-argon mixture transforms the rate-determining step from an ion-molecule interaction to a radical-molecule interaction for both monomer dissociation and polymerization

Radical and ion molecule mechanisms in the polymerization of hydrocarbons and chlorosilanes in RF plasmas at low pressures ( 1.0 torr)

The ion-molecule and the radical-molecule mechanisms are responsible for the dissociation of hydrocarbons, and chlorosilane monomers and the formation of polymerized species, respectively, in the plasma state of a RF discharge. In the plasma, of a mixture of monomer with Ar, the rate determining step for both dissociation and polymerization is governed by an ion-molecular type interaction. Additions of H2 or NH3 to the monomer Ar(+) mixture transforms the rate determining step from an ion-molecular interaction to a radical-molecule type interaction for both monomer dissociation and polymerization processes

Substrate finishing and niobium content effects on the high temperature corrosion resistance in steam atmosphere of CrN/NbN superlattice coatings deposited by PVD-HIPIMS

The main objective of this work was to evaluate the oxidation resistance of three PVD-HIPIMS CrN/NbN coatings, studying the effect of the surface finishing of the substrate and the role of niobium content into the coating composition. CrN/NbN nano-multilayered films on P92 steel were tested at 650°C in pure steam atmosphere. The mass gain was measured at fixed intervals to study their oxidation kinetics. The morphology and thickness of nanoscales were measured by transmission electron microscopy (TEM). Characterization of coatings before and after the thermal treatment was performed by scanning electron microscopy-energy with facilities of dispersive X-ray spectroscopy (SEM–EDX) and X-ray diffraction (XRD). All coatings improved the oxidation resistance of the substrate material, but the best behaviour was exhibited by the CrN/NbN with the high niobium (Nb) content and deposited on the substrate with the finest surface finishing

Effect of Oxygen on Growth and Properties of Diamond Thin Film Deposited at Low Surface Temperatures

Polycrystalline diamond thin films are grown on a p-type Si (100) single crystal substrate at a low surface deposition temperature of 455 °C using a microwave plasma enhanced chemical vapor deposition process in an Ar-rich Ar/H2/CH4 plasma containing different oxygen levels from 0% to 0.75%. The surface deposition temperatures are measured and monitored by an IR thermometer capable of working in a plasma environment without any interference from the plasma emissions. The lower surface deposition temperature at high microwave power of 1300 W and higher gas pressure of 95 torr is achieved by active cooling of the substrate from the backside using a specially designed cooling stage. An enhanced growth rate from 0.19 to 0.63 μm/h is observed with varying oxygen from 0% to 0.75% in the plasma. Diamond grain size also increased from 0.69 μm for the sample with no oxygen to 1.74 μm for the sample with 0.75% oxygen. The diamond films are characterized using x-ray diffraction, environmental scanning electron microscopy field emission gun, Raman spectroscopy, and x-ray photoelectron spectroscopy. The enhanced growth rate is correlated with the enhanced atomic hydrogen to C2 ratio with increasing oxygen concentration in the plasma, which is measured by an in situ optical emission spectroscopy