Thermoluminescent a-CN thin films properties as a function of plasma parameters

Amorphous carbon nitride (a-CN) thin films show luminescent properties that are of interest for many applications. Particularly interesting are their previously reported thermoluminescent characteristics. In order to optimize these properties, the plasma parameters (ion energy, plasma density and type of excited species) were studied in the present work as a function of the laser fluence and the working pressure. The plasma was produced using the fundamental line of a Nd:YAG laser with 28 ns pulse duration focused on a high purity graphite target. The laser fluences used in this work could be varied between 9 and 40 J/cm2. Measurements and deposition of a-CN films were carried out in a nitrogen atmosphere at pressures from 3×10-3 to 7.5×10-2 Torr. We observed an optimum value of pressure, close to 7.5×10-2 Torr, in which the nitrogen incorporation into the film achieved its maximum value close to 29 at. % and the thermoluminescent response of the material, after irradiation with UV becomes evident.