Si impurity in chemical vapor deposited diamond films

Cathodoluminescence (CL) and annealing studies of microwave plasma-assisted chemical vapor deposited (CVD) diamond films were carried out. The annealing behavior of the 1.681 eV (737.4 nm) line in the CL spectra of CVD diamond films grown on Si substrates is compared with that of the GR1 spectral line (1.673 eV) of natural diamond. We determine that these two lines have different origins. The comparison of CL spectra of diamond films grown on different substrates shows that the 1.681 eV peak is due to Si impurity in CVD diamond films.