Effect of C=C content on I-V characteristics of fluorinated amorphous carbon thin films

The current-voltage characteristics of amorphous fluorinated carbon (a-C:F) films prepared by electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) are investigated. The different changes in electric conduction as C = C content is increased are observed for the films with different C-F-x composition. The I-V characteristic follows a nonlinear law of I = aV + bV(n) (n > 1). It shows that the ohmic conduction is dominated at low fields while the space charge limited currents (SCLCs) is dominated at high field. For a-C: F films, the space charge limited currents are relevant to density of state at band-tails controlled by C = C bonds in the films.