TUNGSTEN INCORPORATION IN DIAMOND THIN-FILMS PREPARED BY THE HOT-FILAMENT TECHNIQUE

The films were deposited at 750 °C from CH4 (0.1-1.2%) H2 mixtures, with a hot tungsten (W) filament at a temperature around 2500 K, on unscratched or scratched silicon (Si) substrates. From Rutherford backscattering, W is always incorporated in the films, homogeneously, with a nearly constant total concentration around 1016 atom cm-2. It originates from the thermal decomposition of the carburized W filament at 2500 K. From X-ray diffraction at glancing incidence, the nature and the location of the W compounds are shown to depend strongly on the scratching of the Si substrate and on the composition of the gas mixture. Detailed models are proposed to explain the experimental results. © 1992.