Supersonic Pyrolysis Jets for Diamond Film Deposition
Abstract
We have constructed and tested new higher-temperature ceramic (ZrO2 and SiC) pyrolysis nozzles that can operate continuously at 1700 deg C for several hours. The two successful designs were used to generate intense (10(16) sec-1) beams of CH3 by thermal decomposition of azomethane. We probed the pyrolysate by vacuum-UV photoionization mass spectroscopy and (mass-resolved) resonant multiphoton ionization spectroscopy and determined that the ratio of CH3/C2H2 in our source is greater than 100:1. This should-make it an ideal source of methyl radicals for deposition. A chamber with the pyrolysis nozzle and a separate electric discharge nozzle source of H was constructed. The two jets were directed onto a thermostatted molybdenum foil. Micro-Raman assays (NRL with Jim Butler) of deposited material showed good-quality diamond, but we could not rule out Raman signals from diamond seed crystals with which the surface was scratched. We designed an efficient synthesis for 13CH3-N=N-CH3 as a source of 50% 13C-enriched methyl radicals. Micro-Raman showed no evidence 13C-enriched diamond, from which we conclude that we were previously seeing only the seed crystals. We are currently working on in situ probes to quantify the H concentration, and also trying different substrates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1992
- Accession Number
- ADA251125
Entities
People
- Peter Chen
Organizations
- Harvard University