Evaluation of the diffusion length in polycrystalline silicon by surface photovoltage technique

The Surface Photovoltage (SPV) technique in a expanded spectral region is applied to study perpendicular transport properties in fine (fg/spl sim/1-5 /spl mu/m) and large grained (lg/spl sim/1-3 mm) polycrystalline silicon (p-Si) thin layers made on foreign substrates. A mathematical approach to evaluate the minority carrier diffusion length in complete p-Si solar cells is proposed. This approach allows us to model experimental SPV data by adjusting just one fitting parameter, i.e. the diffusion length. The investigations are carried out on n/sup +/pp/sup +/ cell structures. A beneficial influence on the perpendicular carrier diffusion length is observed in the large grained pc-Si materials. The diffusion length improved more than 4 times from /spl sim/7 /spl mu/m for fg-Si to about /spl sim/34 /spl mu/m for lg-Si.