Effect of the addition of nitrogen gas and annealing on the electrical properties of DLC films deposited by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD)

Abstract

Nitrogenated diamond-like carbon films (a-C:H:N) were deposited on Si-wafers by a rf-PECVD method with the addition of nitrogen to the gas mixture of methane and hydrogen. The effect of the additive nitrogen gas and annealing was investigated in the relationship between the bonding structure and electrical properties of the deposited films. As the flow rate of nitrogen gas and annealing temperature were increased, the film thickness decreased. The electrical conductivity of films increased with an increase in the flow rate of nitrogen up to 10 seem. However a further increase in the flow rate decreased the electrical conductivity rapidly. Also as the annealing temperature was increased, the electrical conductivity of films increased. The structural analysis results show that an increase of the flow rate of nitrogen and annealing temperature favor the formation of sp(2) bonding in the films. Therefore, It has been confirmed that the increase of the electrical conductivity is due to a structural change by graphitization of the films.