Study on an effect of nitrogenation on microstructure properties of hydrogenated amorphous carbon films

The effect of nitrogen incorporation on the microstructure properties of hydrogenated amorphous carbon (a-C:H:N) films prepared by rf sputtering of a graphite target in different Ar-H₂-N₂ atmospheres was investigated by means of photoluminescence and transmittance and reflectance studies. It is found that lower nitrogenation concentration facilitates sp³ bonds and saturates some dangling bonds, so that the photoluminescence peaks shift toward the higher energy side (blue shift) and photoluminescence efficiency increases. At the condition of higher nitrogen dilution, the photoluminescence peaks shift to the lower energy side and photoluminescence efficiency decreases with increasing nitrogen dilution. This might be correlated with the formation of larger size sp ² clusters as well as with the increasing number of nonradiative recombination centers. An anti-Stokes luminescence phenomenon was observed in a-C:H:N films