GROWTH AND OXIDATION OF BORON-DOPED DIAMOND FILMS

Boron-doped diamond films have been grown by the hot filament chemical vapor deposition process. The feed gas was a mixture of argon, bubble d through a solution of B2O3 in ethanol, and hydrogen. The highest gro wth rate was 0.7 mu m/h. The boron concentration in the films depended on the concentration of B2O3 in the ethanol. The highest boron doping level, as measured by secondary ion mass spectroscopy, was 6300 atomi c ppm. Raman spectroscopy and x-ray diffraction both confirmed the pre sence of crystalline diamond in the films. The frequency of the diamon d Raman line decreased with increasing boron concentration. This shift may arise from an interaction of the charged carriers (holes) produce d by the boron doping and the Raman-active optic phonon. The oxidation rates of doped and undoped films were measured by thermogravimetric a nalysis at 700 degrees C in flowing high purity oxygen. Films with a b oron concentration of 6300 ppm oxidized at one-tenth the rate of undop ed diamond. A layer of B2O3, detected on the surface of an oxidized B- doped film, is believed to act as a protective barrier that decreases the oxidation rate.