Multicrystalline silicon layers for photovoltaic applications grown by a modified CVD process

Silicon layers with a grain size of 200 mym can be grown by a modified CVD process at high deposition rates on microcrystalline substrates. Grain boundaries are vertically oriented reaching from the bottom to the surface allowing most of the minority carriers to diffuse without crossing a grain boundary. The doping efficiency of multicrystalline layers is compared to LPCVD-grown films. High Hall mobilities and high effective diffusion lengths are observed. The process is based on chlorosilanes as large silicon feedstock for photovoltaics.