Accession Number : ADA337739
Title : Growth, Characterization and Device Development in Monocrystalline Diamond Films
Descriptive Note : Quarterly technical rept. 1 Oct-31 Dec 97
Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
Personal Author(s) : Davis, R. F. ; Nemanich, R. J. ; Sitar, Z. ; Baumann, P. K. ; Liu, W.
PDF Url : ADA337739
Report Date : DEC 1997
Pagination or Media Count : 70
Abstract : The growth of coalesced, highly-oriented diamond films has been achieved on nickel substrates using a multi-step process consisting of (1) seeding the Ni surface with 0.5 microns diamond powder, (2) annealing at 1100 deg C in a hydrogen atmosphere, and (3) growth at 900 deg C in a mixture of hydrogen and 0.5% methane. An addition of 0.5% methane in the gas phase produced optimum results, as the nucleation density, orientation of diamond particles, and uniformity were substantially improved. Substrates nucleated under these conditions were grown out into coalesced, 30 microns thick films. Both (100) and (111) oriented films showed a high degree of orientation and Raman spectra obtained from these orientations showed intense and narrow diamond signature peaks with FWHMs of 5 and 8/cm, respectively. Nitrogen-doped diamond was deposited by microwave plasma CVD for cold cathode applications and characterized by laser reflectance interferometry, Raman and photo luminescence spectroscopies, and field emission measurements. Initially growth rates of diamond films were enhanced by nitrogen addition, but further nitrogen addition caused a decrease in the growth rate and eventually no diamond deposition was observed for N/C gas phase ratios greater than 70. Raman scattering spectroscopy indicated a decrease in film quality with nitrogen doping. Field emission measurements indicate threshold fields of 70-90 V/mm independent of process conditions. It was also observed that hydrogen leads to a negative electron affinity (NEA) on diamond (100) surfaces while oxygen termination and adsorbate free surfaces exhibit a positive electron affinity. Zirconium deposited on clean and oxygen- or hydrogen containing diamond (100) surfaces also exhibited an NEA.
Descriptors : *THIN FILMS, *DIAMONDS, *CRYSTAL GROWTH, PHOTOLUMINESCENCE, CHEMICAL VAPOR DEPOSITION, SUBSTRATES, NITROGEN, HYDROGEN, FIELD EMISSION, INTERFEROMETRY, ZIRCONIUM, NICKEL, RAMAN SPECTRA, COLD CATHODE TUBES.
Subject Categories : Crystallography
Distribution Statement : APPROVED FOR PUBLIC RELEASE