Structural and Electrical Properties of Amorphous Hydrogen Carbon-Nitrogen Films

Amorphous hydrogenated carbon-nitrogen (a-C:H:(N)) films with different nitrogen contents have been deposited by using rf-sputtering of a high purity graphite target in an Ar-H₂-N₂ atmosphere. Transmittance and reflectance spectra are used to characterize the Tauc gap and absorption coefficients in the wavelength range 0.185-3.2μm. The temperature dependence of conductivity demonstrates a hopping mechanism of the Fermi level in the temperature range of 77-300 K. The density of state at the Fermi level is derived from the direct current conductivity. The photoluminescence properties of a-C:H:N films were investigated. The photoluminescence peak has a blue shift with increasing excitation energy. These results are discussed on the basis of a model in which the different sp² clusters dispersed in sp³ matrices.