Diamond films produced by microwave plasma chemical vapour deposition were exposed, at room temperature, to a flux of thermal H, O or N atoms (plus excited N2*) produced from a microwave-powered beam source. Optical changes were observed in samples treated with N atom doses in the range 3.24 × 1017-1.67 × 1018 atoms cm-2, whereas samples treated with H atoms (1.64 × 1022 atoms cm-2) and O atoms (2.81 × 1017 atoms cm-2) showed no obvious alteration. Scanning electron micrographs of the N-treated samples showed etching of the faceted crystallites. This resulted in reduced surface roughness as evidenced by stylus profilometry. X-Ray photoelectron spectroscopy and laser ionization mass analysis both detected the presence of nitrogen in the surface layers in these samples. Fourier transform IR analysis showed this to be covalently bound as both NH and CN. Cathodoluminescence studies did not show the characteristic emission lines associated with nitrogen vacancy or nitrogen interstitial centres. Electrical conductivity measurements by four-point probe techniques showed an increase in the resistivity of as-prepared films after O and H atom treatment. For a dose of 1.64 × 1022 H atoms cm-2, the electrical resistivity was dramatically increased to greater than 2 × 105 O cm. In contrast, etching of the films by an H2 microwave plasma for 30 min immediately after deposition at 835 °C produced films with a low resistivity of around 50 O cm. The resistivity was increased to 5.8 × 103 O cm after an additional 3 h, but did not attain the values produced by room temperature thermal H atom treatment. © 1995.
|Number of pages||6|
|Journal||Diamond and Related Materials|
|Publication status||Published - 15 Apr 1995|
- Atomic species
- Diamond films