Optoelectronic properties and carrier transport mechanisms in amorphous SiCN

Abstract Amorphous silicon carbon nitride (a-SiCN) films were prepared on boron-doped silicon and quartz substrates by plasma-enhanced chemical vapor deposition. The films were characterized by using X-ray diffraction spectroscopy, atomic force microscopy, Fourier transform infrared spectroscopy, as well the results of the measurements of optical spectra, photoluminescence (PL) and current-voltage characteristics. The films demonstrate high optical transparency and the energy gap ~ 3.4 eV. The PL spectra consist of three bands at 395, 500 and 526 nm that are caused by the electronic recombination in the Si-C-N-H-O network. Forward and reverse current-voltage characteristics were measured in the temperature range of 196–353 K. The forward current is explained by unipolar space-charge-limited (SCL) current mechanism with an exponential distribution of trap states in a local energy band. The reverse current is limited by the depletion region in the p-Si substrate. Basic electrical parameters of a-SiCN layers are determined from the SCL current measurements.