Optoelectronic properties of highly conductive microcrystalline SiC produced by laser crystallisation of amorphous SiC

The optoelectronic properties of undoped and doped microcrystalline silicon carbide thin films, prepared by excimer (ArF) laser crystallisation of plasma enhanced chemical vapour deposited hydrogenated amorphous silicon carbide, are analysed. All films show more than six orders of magnitude increase relative to the conductivities before the laser crystallisation. It is shown that the increase in conductivity is not predominantly due to the activation of dopant atoms. However, dopant sites, but not carbon content (up to 30 at%), play an important role in electrical transport in μc-SiC. We also report the observation of blue photoluminescence at room temperature from the undoped laser irradiated samples having a carbon content of 35 at%. The spectrum exhibits two visible peaks (1.8 eV and 2.6 eV), while the as-deposited films show only the 1.8 eV peak.