High rate deposition of silicon thin films by hot wire cell method for solar cell applications

Hot wire cell method has been newly developed and successfully applied to grow polycrystalline and amorphous Si thin films with relatively high growth rates of 0.4-2.0 nm/s. It is found that polycrystalline Si films can be obtained at substrate temperatures of 175-400°C without a hydrogen dilution when the filament temperature is 2000-2100°C. Valency control has been carried out by using of PH ₃ and B₂H₆. Up to now, high conductivities of 13 S/cm and 4 S/cm have been achieved for n-type and p-type polycrystalline Si thin films, respectively. Polycrystalline Si and a-Si solar cells prepared with the deposition rates of 0.4-1.0 nm/s showed the efficiencies of ~1% and 4.3%, respectively. We found by SIMS analysis that the high concentration of O and C atoms is incorporated into the film which limits the present cell performances