Boron carbide films are increasingly being investigated for their application in new generation neutron detectors. It is implemented as conversion layer for neutrons and emerging as a potential alternative to ³He based detectors. This work reports synthesis of boron carbide (B_xC) films from ortho-carborane (o-C₂B₁₀H₁₂) by radio frequency (RF) plasma enhanced chemical vapour deposition (PECVD) technique. Dependence of chemical composition, stoichiometry and total macroscopic cross section (Σ_t) has been studied as a function of self-bias on the substrate, varied in the range -75 V to -175 V. Films were characterized by 3D optical profilometry, X-ray photoelectron spectroscopy (XPS), proton elastic backscattering spectrometry (p-EBS), Fourier transform infra-red spectroscopy (FTIR) and Field Emission Scanning Electron Microscope (FESEM). Characterization results show noticeable change in the bulk as well as surface chemical composition, surface morphology and film stoichiometry with self-bias. Neutron transmission measurements exhibit increase in Σ_t from 170.47 cm^-1 for -75 V film to 273.38 cm^-1 for -175 V film with self-bias.