Nanocrystalline silicon carbide films for solar photovoltaics: The role of dangling-bond defects

Thin films of microcrystalline hydrogenated silicon (µc-Si:H) and nanocrystalline silicon carbide (nc-SiC:H) provide a new class of advanced nanostructured materials for solar photovoltaic (PV) devices. We have worked on the fabrication, characterization, and appli- cation of these materials for thin film PV solar cells based on amorphous silicon. Here we present an overview of the preparation and characterization methods for heterogeneous SiC:H-based layers. Hydrogenated nc-SiC:H thin film materials with high crystalline volume fraction were deposited using photo-assisted chemical vapor deposition (photo-CVD) tech- nique. The behavior of spin-containing dangling-bond (DB) defects was performed using electron spin resonance (ESR) and transport measurements as a function of sample crys- tallinity, doping level, and temperature. The electronic and structural properties of intrinsic and doped µc-Si:H and nc-SiC:H thin films are reviewed with the emphasis of the essential role of DB defects on the photoelectronic transport parameters.