Growth and characterisation of amorphous carbon films doped with nitrogen

Hydrogenated amorphous carbon (a-C:H) thin films are of interest to the electronics industry as possible inexpensive semiconductors, especially for device passivation. Nitrogenation is a promising method for the doping of the films. We have grown a-C:H films on the earthed electrode of a radio frequency driven plasma enhanced chemical vapour deposition system using methane, helium and a range of nitrogen concentrations as precursor gases. We subsequently studied the composition of the films with heavy ion Elastic Recoil Detection analysis. Nitrogen concentrations increasing from 0 to 8 at.% with N flow rate are observed, with a corresponding decrease of the carbon concentration. The hydrogen concentration remains approximately constant as a function of nitrogen flow into the chamber. Fourier Transform Infrared analysis confirmed that with increasing nitrogen content there is a C-N and N-H bond concentration increase. This is accompanied by a reduction in the C-H bond concentration