Structural and band tail state photoluminescence properties of amorphous SiC films with different amounts of carbon

Amorphous silicon carbide films are deposited by the plasma enhanced chemical vapour deposition technique, and optical emissions from the near-infrared to the visible are obtained. The optical band gap of the films increases from 1.91 eV to 2.92 eV by increasing the carbon content, and the photoluminescence (PL) peak shifts from 1.51 eV to 2.16 eV. The band tail state PL mechanism is confirmed by analysing the optical band gap, PL intensity, the Stocks shift of the PL, and the Urbach energy of the film. The PL decay times of the samples are in the nanosecond scale, and the dependence of the PL lifetime on the emission energy also supports that the optical emission is related to the radiative recombination in the band tail state.