Photoconductivity study of amorphous carbon nitride films for opto-electronics devices

Single layered amorphous carbon nitride (a-CNx) films and a multilayered a-CNx film were prepared by reactive radio frequency magnetron sputtering of a graphite target and nitrogen gas. This paper describes the optical, electrical and opto-electrical properties of the a-CNx films. The optical band-gap of the single layered films increased with increasing nitrogen concentration, which was controlled through the deposition temperature. The photo-sensitivity values, a ratio of photo- and dark-conductivities, ranged from 2.2 to 6.0. In the multilayered film consisting of four a-CNx layers deposited at different temperatures, the photo-sensitivity of the multilayered film was over 1.2 times as compared with that of the single layered films.

Research highlights
► Increasing deposition temperature will decrease the optical gap of a-CNx films.
► The optical band-gap of a-CNx films depends on the nitrogen concentrations.
► Multilayered a-CNx films have a graded optical band-gap.
► A multilayered structure in a-CNx effects an improvement of photo-sensitivity.