Thin Solid Films 395 (2001) 152–156 0040-6090/01/$ - see front matter  2001 Elsevier Science B.V. All rights reserved. PII:S0040-6090 Ž 01 . 01244-5 High-rate deposition of silicon thin-film solar cells by the hot-wire cell method Makoto Konagai *, Takeshi Tsushima , Myoung-Kyu Kim , Koichi Asakusa , Akira Yamada , a, a a a a Yuriy Kudriavtsev , Antonio Villegas , Rene Asomoza b b b Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552, Japan a Electrical Engineering Department, Center for Research and Advanced Studies, Apdo. Postal 14-740, 07000 Mexico, D.F., Mexico b 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 . It was found that polycrystalline Si films can be obtained at substrate temperatures of 175–4008C y1 without hydrogen dilution when the filament temperature is 2000–21008C. Valency control has been carried out using PH and 3 B H . Up to now, high conductivities of 13 and 4 S cm have been achieved for n- and p-type polycrystalline Si thin films, y1 26 respectively. Superstrate-type polycrystalline Si and amorphous Si solar cells prepared with deposition rates of 0.4–1.0 nm s y1 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 10 –10 cm , is incorporated into the film, which limits the performance of the present 20 21 y3 cell.  2001 Elsevier Science B.V. All rights reserved. Keywords: Amorphous materials; Chemical vapor deposition (CVD); Solar cells; Hot-wire chemical vapor deposition (HW-CVD) 1. Introduction At present, the deposition rate is typically approxi- mately 0.1–0.3 nm s for amorphous Si (a-Si) and y1 polycrystalline Si thin-film solar cells. At these current deposition speeds, the mass production of solar cells introduces various problems to manufacturing plants. To reduce the proportion of equipment costs in the manu- facturing of Si-based thin-film solar cells, the deposition rate must be increased. The target value for deposition rate is 1–2 nm s for these solar cells. The first y1 author’s group proposed the hot-wire cell method, and exhaustively tested the material properties of a-Si and polycrystalline Si thin films prepared using SiH gas 4 w1x. The significant difference between our hot-wire cell method and previous HW-CVD works is the layout of the HW filament. In the hot-wire cell method, the filamentisperpendiculartothesubstrateholder.Because *Correspondingauthor.Tel.: q81-3-5734-2554; fax: q81-3-5734- 2897. E-mail address: konagai@pe.titech.ac.jp (M. Konagai). of the layout of the filament, the reactant gas is decom- posed effectively while traveling in the filament and the decomposition rate of the reactant gas is increased. In this method, sufficient atomic hydrogen is supplied from the decomposition of SiH at the filament. Therefore, 4 polycrystalline Si film can be obtained without hydrogen dilution. In this study, we have investigated the structural and electrical properties of a-Si and polycrystalline Si thin films deposited by the hot-wire cell method using SiH 4 without hydrogen dilution. Furthermore, in order to evaluate the films deposited as a solar cell material, we fabricated a p–i–n solar-cell structure. We describe preliminary results of Si thin-film solar cells, where the films were deposited at rates of approximately 1 nm s. y1 2. Deposition mechanism In this method, the crystallinity of films is signifi- cantly affected by the total pressure of the deposition chamber. For film deposited at a total pressure of less