Effect of nitrogen pressure on the performance of a-C:N/p-Si photodetector prepared by pulsed laser deposition

Abstract

Amorphous nitrogen doped nanostructured carbon a-C:N films were prepared on glass and silicon substrates by pulsed laser ablation of graphite target using Nd:YAG laser pulses at laser fluence of 11.1J/cm2. The effect of nitrogen gas pressure (2.5×10−2–7.5×10−1) mbar on the structural, optical and electrical properties of a-C:N thin films was investigated by using X-ray diffraction XRD, Scanning electron microscopy (SEM), energy dispersive x-ray EDX, Fourier transformation infrared spectroscopy FT-IR, Raman spectroscopy, UV–vis transmittance and Hall effect. The film prepared at higher nitrogen pressure exhibited maximum optical transmittance and the optical band gap decreasing from 2 to 1.75eV as nitrogen pressure increases from 2.5×10−2 to 7.5×10 −1mbar. Raman data confirms that the ID/IG ratio of a-C:N films increases as nitrogen pressure increase. Increases the nitrogen pressure leads to increasing the electron mobility and decreasing the electrical resistivity of deposited film. The electrical and photoresponse properties of a-C:N/Si heterojunction photodetectors was studied as function of nitrogen gas pressure.