Influence of diborane on the growth rate and phase stability of diamond films

The influence of the addition of high concentrations of diborane in the sou rce gas on the growth of diamond films by chemical vapour deposition is inv estigated. For polycrystalline films grown on silicon, a decrease in the de position rate is observed for boron concentration higher than B/C = 6000 pp m, and a spurious amorphous carbon phase appears above B/C = 10 000 ppm. Fo r homoepitaxial growth on type Ib diamond, the deposition rate is nearly co nstant up to B/C = 4000 ppm. With a higher boron concentration the films ar e polycrystalline. From the comparison of these two growth conditions shows we ascribed the decrease in the deposition rate, the appearance of a spuri ous phase and the loss of epitaxy to a modification of the plasma chemistry . (C) 1998 Elsevier Science Ltd. All rights reserved.