Nitrogen modification of hydrogenated amorphous carbon films

The effect of nitrogen addition on the structural and electronic properties of hydrogenated amorphous carbon (a-C:H) films has been characterized in terms of its composition, sp(3) bonding fraction, infrared and Raman spectra, optical band gap, conductivity, and paramagnetic defect. The variation of conductivity with nitrogen content suggests that N acts as a weak donor, with the conductivity first decreasing and then increasing as the Fermi level moves up in the band gap. Compensated behavior is found at about 7 at. % N, for the deposition conditions used here, where a number of properties show extreme behavior. The paramagnetic defect density and the Urbach tailwidth are each found to decrease with increasing N content. It is unusual to fmd alloy additions decreasing disorder in this manner. (C) 1997 American Institute of Physics.