Conductivity and Hall effect in diamond-like carbon (DLC) thin films

A set of four nitrogen doped films were successfully grown using the DC saddle field deposition system. Samples grown under these conditions were classified as hard a-C:H with a Tauc gap of about 1eV and resistivity of 1.43 GO·cm at 25°C. Upon addition of nitrogen the growth rate decreased and films exhibited an increase in conductivity in conjunction with a slight increment in Tauc gap and optical bandgap. A shift in the Fermi level towards the conduction band was also observed.; Hall measurements were performed only on the sample deposited using a 30% gas fraction of nitrogen. Hall mobility was about 35 cm2/V -1·s-1. Hall coefficient showed a negative sign and an exponential behaviour suggesting electrons as the majority carrier in the conduction process.; Decrease in the activation energy and in the film's disorder accompanied by an increment in conductivity, optical bandgap and mobility suggest that nitrogen is acting as a substitutional dopant.