Optical Emission Imaging and Modeling Investigations of Microwave-Activated SiH/H and SiH/CH/H Plasmas.

Silicon is a known trace contaminant in diamond grown by chemical vapor deposition (CVD) methods. Deliberately Si-doped diamond is currently attracting great interest because of the attractive optical properties of the negatively charged silicon-vacancy (SiV) defect. This work reports in-depth studies of microwave-activated H plasmas containing trace (10-100 ppm) amounts of SiH, with and without a few % of CH, operating at pressures and powers relevant for contemporary diamond CVD, using a combination of experiment (spatially resolved optical emission (OE) imaging) and two-dimensional plasma chemical modeling.

Imaging and Modeling the Optical Emission from CH Radicals in Microwave Activated C/H Plasmas.

We report a combined experimental/modeling study of optical emission from the AΔ, BΣ, and CΣ states of the CH radical in microwave (MW) activated CH/H gas mixtures operating under a range of conditions relevant to the chemical vapor deposition of diamond. The experiment involves spatially and wavelength resolved imaging of the CH(C → X), CH(B → X), and CH(A → X) emissions at different total pressures, MW powers, C/H ratios in the source gas, and substrate diameters. The results are interpreted by extending an existing 2D (, ) plasma model to include not just electron impact excitation but also chemiluminescent (CL) bimolecular reactions as sources of the observed CH emissions.

Spatially Resolved Optical Emission and Modeling Studies of Microwave-Activated Hydrogen Plasmas Operating under Conditions Relevant for Diamond Chemical Vapor Deposition.

A microwave (MW) activated hydrogen plasma operating under conditions relevant to contemporary diamond chemical vapor deposition reactors has been investigated using a combination of experiment and self-consistent 2-D modeling. The experimental study returns spatially and wavelength resolved optical emission spectra of the d → a (Fulcher), G → B, and e → a emissions of molecular hydrogen and of the Balmer-α emission of atomic hydrogen as functions of pressure, applied MW power, and substrate diameter. The modeling contains specific blocks devoted to calculating (i) the MW electromagnetic fields (using Maxwell's equations) self-consistently with (ii) the plasma chemistry and electron kinetics, (iii) heat and species transfer, and (iv) gas-surface interactions.

What [plasma used for growing] diamond can shine like flame?

Diamond synthesis by chemical vapour deposition (CVD) from carbon-containing gas mixtures has by now long been an industrial reality, but commercial interest and investment into the technology has grown dramatically in the last several years. This Feature Article surveys recent advances in our understanding of the gas-phase chemistry of microwave-activated methane/hydrogen plasmas used for diamond CVD, including that of added boron-, nitrogen- and oxygen-containing dopant species. We conclude by considering some of the remaining challenges in this important area of contemporary materials science.

Optical Emission from C Anions in Microwave-Activated CH/H Plasmas for Chemical Vapor Deposition of Diamond.

Visible emission from C(BΣ) anions has been identified underlying the much stronger Swan band emission from neutral C(dΠ) radicals (henceforth C* and C*, respectively) in MW-activated C/H/(Ar) plasmas operating under conditions appropriate for the chemical vapor deposition (CVD) of diamond. Spatially resolved measurements of the C* and C* emissions as functions of the C/H/(Ar) ratio in the input gas mixture, the total pressure, and the applied MW power, together with complementary 2-D(r, z) plasma modeling, identifies dissociative electron attachment (DEA) to CH radicals in the hot plasma as the dominant source of the observed C* emission. Modeling not only indicates substantially higher concentrations of CH anions (from analogous DEA to CH) in the near-substrate region but also suggests that the anion number densities will typically be 3-4 orders of magnitude lower than those of the electrons and partner cations, i.