Improved steady-state photocarrier grating in nanocrystalline thin films after surface-roughness reduction by mechanical polishing

We detect elastic optical scattering resulting from the surface roughness of nanocrystalline silicon by a poor optical grating in the steady-state photocarrier grating experiment. The small variation of the experimental sampling function reduces the reliability of the ambipolar diffusion length measurements in this case. We demonstrate that the reduction in surface roughness of nanocrystalline silicon by polishing reduces optical scattering, improves the grating quality, and allows a reliable determination of the ambipolar diffusion length, making the experiment attractive for characterizing nanocrystalline silicon and other semiconductors which exhibit optical scattering. (C) 1998 American Institute of Physics.