Uniformity and bandgap engineering in hydrogenated nanocrystalline silicon thin films by phosphorus doping for solar cell application

摘要

Micro-Raman mapping with a spatial resolution of micrometer and room-temperature visible photoluminescence (PL) has been carried out on phosphorus-doped hydrogenated nanocrystalline silicon (nc-Si:H) thin films grown by plasma enhanced chemical vapor deposition. Both the thin film uniformity and structural properties, i.e., the distribution of grain sizes and crystalline volume fraction, with different doping concentrations are revealed and physically interpreted based on the growth mechanism. The observed uniformity has been further confirmed by the PL measurements, and the bandgap engineering of the nc-Si:H thin films has been discussed from the dependence of PL peak energy on doping concentration. These results provide implications to realize control of properties of nc-Si:H by P-doping under optimized growth conditions for solar cell application.