Development of p-type microcrystalline silicon carbon alloy films by the very high frequency plasma-enhanced chemical vapor deposition technique

Abstract

We developed p-type μc-silicon carbon alloy thin films by the very high frequency plasma-enhanced chemical vapour deposition technique using a SiH₄, H₂, CH₄, and B₂H₆ gas mixture at low power (55 mW/cm²) and low substrate temperatures (150–250 °C). Effects of substrate temperature and plasma excitation frequency on the optoelectronic and structural properties of the films were studied. A film with conductivity 5.75 Scm⁻¹ and 1.93 eV optical gap (E₀₄) was obtained at a low substrate temperature of 200 °C using 63.75 MHz plasma frequency. The crystalline volume fractions of the films were estimated from the Raman spectra. We observed that crystallinity in silicon carbon alloy films depends critically on plasma excitation frequency. When higher power (117 mW/cm²) at 180 °C with 66 MHz frequency was applied, the deposition rate of the film increased to 50.7 Å/min without any significant change in optoelectronic properties.