Photovoltaic properties of polycrystalline silicon films thickened by laser melting

During RF CVD of a-Si:H onto glass an Ar⁺ laser beam was scanned to crystallize a seed layer. Subsequently every 20 nm new deposited a-Si:H was molten by one light pulse from a KrF laser, so that the laser processing did not take any additional time. A highly conducting p⁺ region close to the glass as transparent electrode and a p⁺pn junction within the film were deposited without a doping gas. REM, TEM images and XRD measurements confirmed an epitaxial growth of large crystallites. The self structured silicon/glass interface and film surface show increased scattering which supports light absorption. Transients of open circuit voltage after a pulsed generation by UV light at the p⁺, as well as at the n side, were contactless sensed to evaluate the PV quality of films as deposited. A lifetime of more than 5 μs and a diffusion length for holes of more than 25 μm were determined