Thermoluminescent response of carbon nitride thin films deposited by laser ablation

The effect of a high purity nitrogen working pressure on the properties of CNx thin films grown by laser ablation has been studied. Different analytical techniques were employed to characterize the films including: Thermoluminescence (TL) measurements, Raman spectroscopy, Ion Beam Elastic Dispersion, UV–Vis spectrophotometry, FTIR, and ellipsometry. Analysis of the data shows that in spite of the fact that the system base pressure was better than 10−6 Torr and no hydrogen was intentionally introduced into the chamber, incorporation of hydrogen into the film was observed but only when a nitrogen gas flow was used. In this way the deposited amorphous carbon nitride films, with a nitrogen content of up to 20%, almost always contained a significant quantity of hydrogen (22%). The films show a thermoluminescent signal with peaks at 150 and 290 °C after irradiation with UV. When 60Co gamma rays were used, only the 290 °C peak was observed. The Ion Beam Elastic Dispersion analysis showed the presence of lower hydrogen and nitrogen concentrations. The prepared material has a potential application as an ultra-thin TL dosemeter, and since carbon has a low atomic number it can be considered as soft tissue equivalent material for such applications.