Photoluminescence in CVD diamond films

Photoluminescence (PL) measurements of CVD diamond films reveal well-define d lines at 1.68, 1.945 and 2.156 eV, in addition to broad red, green and bl ue bands. The 1.68 eV line is attributed to Si-related center and when acco mpanied by the red band, shows a strong dependence of its intensity on the excitation photon energy. The 2.156 and 1.945 eV lines are assigned to nitr ogen-vacancy complexes. The absence of the 1.945 eV line for samples with l ow nitrogen content shows that the formation of the 2.156 eV center is more favorable than of the 1.945 eV center. Blue, green and red broad PL bands are attributed to dislocations, boron-related defect and to nitrogen, respe ctively. Results on intensity and excitation photon energy dependences of P L measured for CVD and shock-synthesis diamond showed that a donor-acceptor recombination model cannot explain the broad band PL in our samples.