High-rate deposition of silicon thin-film solar cells by the hot-wire cell method

Abstract

The hot-wire cell method has been developed to grow polycrystalline and amorphous Si thin films with relatively high growth rates of 0.4–3.0 nm s−1. It was found that polycrystalline Si films can be obtained at substrate temperatures of 175–400°C without hydrogen dilution when the filament temperature is 2000–2100°C. Valency control has been carried out using PH3 and B2H6. Up to now, high conductivities of 13 and 4 S cm−1 have been achieved for n- and p-type polycrystalline Si thin films, respectively. Superstrate-type polycrystalline Si and amorphous Si solar cells prepared with deposition rates of 0.4–1.0 nm s−1 showed efficiencies of 1.6 and 4.3% under AM1.5 illumination, respectively. We found by SIMS analysis that a high concentration of O and C atoms, of the order of 1020–1021 cm−3, is incorporated into the film, which limits the performance of the present cell.