HIGH-ENERGY PHOTOLUMINESCENCE IN LOW TAUC GAP A-C-H-N

In this letter, the photoluminescence signals in low optical gap (belo w 2.0 eV) a-C:H:N films were investigated. Films were deposited by r.f . sputtering of a graphite target in Ar-H-2-N-2 atmospheres having dif ferent Ar/N-2 flow rate ratios. We have found photoluminescence signal s of high intensity and having a peak energy well over 2.0 eV. These r esults are discussed on the basis of a model in which the sp(2) cluste rs are considered as luminescence centres. Nitrogenation effect upon t he luminescence centres and the luminescence intensity correlation wit h nitrogen concentration are also discussed, in the light of the prese nted model.