Boron carbide films have been fabricated from pentaborane (B5H9) and methane using plasma enhanced chemical vapor deposition (PECVD). Availability of high quality specimens has facilitated analysis of electronic and optical properties. We have undertaken measurements of photoluminescence spectra and infra-red band-edge absorption. Results show that the bandgap is strongly influenced by the ratio of boron to carbon. There is evidence for the existence of shallow trapping levels.