Some aspects of nitrogen doped amorphous carbon thin films

Optical, structural and photovoltaic properties of amorphous carbon (a-C) thin films deposited on p-type silicon (p-Si) and quartz substrates by microwave (MW) surface-wave plasma (SWP) chemical vapor deposition (CVD) were analyzed in this paper. Argon (Ar: 200 sccm) was used as carrier gas while acetylene (C2H2: 20 sccm) and nitrogen (N: 0 and 10 sccm) were used as plasma source. Analytical methods such as X-ray photoelectron spectroscopy (XPS), Raman and UV-visible spectroscopy were employed to investigate the structural and optical properties of the a-C thin films respectively. The optical gaps of the films were tailored from 1.2 eV to 0.9 eV with nitrogen doping. Nitrogen doped a-C (a-C:N) thin film showed the photoconductivity action under white light illumination and hence Au/a-C:N/p-Si/Au heterojunction solar cell was fabricated with 0.23 V open circuit voltage, fill factor 25 and efficiency 5.7* 10⁻³ %.