CRYSTAL-GROWTH OF EPITAXIAL CVD DIAMOND USING C-13 ISOTOPE AND CHARACTERIZATION OF DISLOCATIONS BY RAMAN-SPECTROSCOPY

C-13 epitaxial diamond films have been grown on C-13-type IIb diamond substrates doped with boron, using electron assisted chemical vapor deposition. The relation between etch pits due to dislocations in C-13 diamond film and the broadening of the first-order Raman peak was examined. The reactant gas was (CH4)-C-13 of > 99% purity. The substrate temperature was varied from 943 to 1300-degrees-C. The uneven surface morphology was confirmed by atomic force microscopy (AFM) and laser microscopy. From 943 to 1030-degrees-C, etch pit rows along [100] were observed. At 991-degrees-C, the etch pit density on a row was 3300 to 5000 pits/cm. The Ar+ laser beam was focused on a transparent area near the row of etch pits, where the boron impurity of the substrate is less than several 10 ppm. The first-order Raman line of C-13 epitaxial diamond film was broadened to 3.6-4.0 cm-1. The line broadening was 50-90% compared with that of the C-12 diamond substrate, 2.1-2.4 cm-1. At 1300-degrees-C, there were very few etch pit rows. The broadening was decreased to 23-25%. The slit width was 1.2 cm-1.