Study of large-grained n-type polycrystalline silicon thin films made by the solid phase crystallization method

N-type polycrystalline silicon (poly-Si) films with large grains exceeding 30 μm in width are successfully prepared by the solid phase crystallization (SPC) technique on glass through a control of the PH₃ gas flow rate. The grains in the poly-Si films are investigated by electron backscatter diffraction (EBSD) and are found to be randomly oriented, whereby the average grain size ranges from 4.3 to 18 μm. The grain size in the poly-Si film increases with increasing PH₃ gas flow rate. The impact of the PH₃ flow rate on the crystal quality and the electronic properties of the poly-Si thin-film solar cells are systematically investigated using UV reflectance and Hall effect measurements. A Hall mobility of about 71.5 cm²/Vs for n⁺ doped poly-Si films with a carrier concentration of 2.3×10¹⁹ cm^-3 is obtained.