Physical Properties of Reactively Sputter-Deposited C-N Thin Films

The aim of this work was to prepare and study amorphous carbon nitride (CNx) films. Films were deposited by reactive magnetron radiofrequency (RF) sputtering from graphite target in argon and nitrogen mixture discharge at room temperature. The ratio of the gas flow rate was varied from 0.1 to 1. Deposited films were found to be amorphous. Highest Nitrogen concentration achieved was 42 atomic percent which is very rare and therefore, the highest nitrogen to carbon atomic ratio was 0.76. The incorporation of nitrogen promoted the clustering of diamond-like sites at the expense of graphitic sites leading to a decrease in disorder. The film surface became rougher with the increase nitrogen concentration. Films were optically transparent in the 200-900 nm wavelength range with a wide gap varying between 3.59 and 3.63 eV. There was an increase in resistivity from 15 to 87.4 × 10^-3 Ω. cm for a-CNx thin films for 0.1 RF 0.8 and a less decrease for RF 0.8. Pore size increased in the films, but had little influence on band gaps. On the other hand, increased pore size reduced electrical interaction between particles by increasing resistivity