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The surface chemistry of the Si:H:Cl film formation by rf plasma-enhanced chemical vapor deposition of SiH2Cl2 and SiCl4 systems is demonstrated at low tempeatures of 90–140°C. There exists a threshold substrate temperature Tth for the phase transition from amorphous to nanocrystalline silicon, nc-Si, which decreases from 110°C to 70°C with increasing H2 flow rate in the SiH2Cl2 system. On the other hand, Tth is almost independent of the H2 flow rate in the SiCl4 system along with a higher disorder in the a-Si network than in the SiH2Cl2 system. The degree of the chlorine termination in SiClx (x=1, 2) is at the growing top surface highly related to the degree of disorder in the Si-network. The disorder-induced phase transition to nanocrystalline is demonstrated from film deposition studies from the SiH2Cl2 and SiCl4 systems.

A novel p-type hydrogenated chlorinated nanocrystalline silicon (nc-Si:H:(Cl)) film was fabricated from chlorinated materials, i.e., SiH2Cl2 and SiCl4,by rf plasma-enhanced chemical vapor deposition. These p-type nc-Si:H:(Cl) films showed high conductivities of 10–50 S/cm under 3000–5000 ppm B2H6-mixing concentrations with lower optical absorption in the visible region, while maintaining a high film crystallinity. No marked darkening of the ZnO:Al layer was observed after deposition of the p-type nc-Si:H:(Cl) layer fabricated from SiH2Cl2 and SiCl4 compared to the p-type Si:H film fabricated from SiH4. The origin of the low optical absorption in p-type nc-Si:H:(Cl) is demonstrated along with the performance of a p–i–n structure amorphous silicon solar cell.