CARBON DOPING OF MBE GAAS AND GA0.7AL0.3AS FILMS USING A GRAPHITE FILAMENT

Carbon doped GaAs and Ga0.7Al0.3As films have been grown by molecular beam epitaxy using a resistively heated graphite filament. At moderate doping levels, the effect on carbon doping of the V/III flux ratio and the nature of the arsenic species was found to be minor. The GaAs films were doped from 1 x 10(15) to 5 x 10(19) cm-3 and the resulting hole mobilities were equivalent to beryllium doped films. Excellent doping uniformity was obtained for 3-inch diameter films. Ga0.7Al0.3As films were also doped from 9 x 10(17) to 3.4 x 10(19) cm-3. For the highest carbon doped films, lattice contractions were observed which were greater than for beryllium doping. The lattice contractions were analyzed with a model using tetrahedral covalent radii.