Estimation of the silicon concentration by an optical way in polycrystalline CVD diamond

The concentration of radiative silicon centres in polycrystalline diamond films grown on silicon wafers was tentatively measured by their laser-induced luminescence (PL) at 1.681 eV. The total area under the PL line at room temperature is proportional to the amount of radiative Si point-defects in the volume excited by the laser beam. This amount was normalized to the area (expressed with the same arbitrary unit) under the diamond Raman line at 1332 cm–1 obtained simultaneously on the same set-up and compared to the absolute concentration determined by SIMS experiments. A linear relationship was obtained be- tween the normalized PL area and the averaged SIMS values. Room temperature slope values (αlaser) of the linear relationship were obtained for the following laser lines: 632.8 nm, α633 = 7.8 E + 15, 514.5 nm, α514 = 2.5 E + 16 and for 488 nm, α488 = 5.5 E + 16 at/cm3.SIMS profiles obtained in the different layers indicate that the distribution of silicon in the layers is a consequence of thermally activated diffusion from the silicon substrate during film growth. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)