UHV μ-electron beam evaluation of the CVD diamond particles grown on Si(001)

The electronic and structural properties of diamond particles chemical. vapor deposition (CVD)-grown on Si(001) surfaces were studied using a scanning probe mu -electron beam with SEM, RHEED, secondary-electron spectroscopy (SES) and Anger-electron spectroscopy in ultra-high-vacuum (UHV) conditions. The CVD grown diamond particles studied were made with a source gas of either CO/H-2 (sample A) or CH4/H-2 (sample B) on Si(001). The UHV-SEM images showed that sample A was composed of diamond particles with well-determined row-index surfaces while those for sample B with poorly determined surfaces. mu -RHEED patterns from diamond single-crystallites for sample A showed well-developed. Kikuchi-bands together with surface spots indicating a good order of diamond framework near the surface. The diamond crystallites of-sample A Showed varieties of SES spectra and only a small fraction of them had negative electron affinity (NEA) although no differences are found in RHEED. The SES spectra for sample B showed that essentially all the diamond particles are NEA. It is found that the Fermi-level is located at similar to 1.0 eV above the valence band maximum for NEA diamond particles and similar to 1.5 eV for PEA ones. The change in electron affinity and the origin of surface conductive layers present on as-grown CVD diamonds are discussed in terms of the Fermi-level positions found presently. (C) 2001 Elsevier Science B.V. All rights reserved.