Photoconductivity and highly selective ultraviolet sensing features of amorphous silicon carbon nitride thin films

Photoconductivity of amorphous silicon carbon nitride (a-SiCN) as a function of incident photon energies has been studied. A metal-semiconductor-metal photodetector device based on the a-SiCN thin film demonstrates excellent selective ultraviolet sensing features. A large photo-to-dark current ratio about 5000 and a relative quantum efficiency about ∼105 under illumination of the 250nm light source and a bias voltage of 5V were observed. A model based on the heterogeneous structure in the a-SiCN thin film which consists of π−π* bands and σ−σ* bands was introduced to account for the observed photoconductive transport properties.