RELATION BETWEEN THE DISLOCATIONS IN CHEMICALLY VAPOR-DEPOSITED DIAMOND AND THE LINEWIDTH OF THE RAMAN-SPECTRUM

The C-13 epitaxial diamond thin films were grown on the (100) planes o f synthesized C-12 type IIb diamond substrates by electron-assisted ch emical vapour deposition. A chemical etching pre-treatment was perform ed on the substrate to clean the surface. The etchant used consisted o f potassium nitrate and potassium chloride. The reactant gas used was a 1% C-13 isotope CH4-H2 mixture gas in order to distinguish between t he Raman spectra of the C-13 epitaxial film and the C-12 diamond subst rate. Epitaxial growth of thin films was confirmed by reflection high energy electron diffraction patterns. Etch pits related to dislocation s were observed with Nomarski optical microscopy and the use of wet et ching. A relation between the etch pit density and the first-order Ram an spectrum of the epitaxial CVD diamond was found. When the etch pit density increased from 9.8 x 10(4) to 4.7 x 10(5) cm-2, the full width at half-maximum of the first-order Raman spectrum broadened from 4.9 to 6.6 cm-1. At the same time, the peak wavenumber of the Raman spectr a increased from 1284.3 to 1286.8 cm-1. The slit width was 1.2 cm-1.