Aluminum-seeded growth of microcrystalline Si thin film onto SnO2 substrate

To improve the crystallinity of thin boron-doped microcrystalline Si (p-mu c-Si:H) films at an initial growth stage, we tried an Al-seeding method, which is to deposit an ultrathin (similar to 50 Angstrom) Al layer onto a transparent conducting oxide before preparing the p-mu c-Si:H film by using a mercury-sensitized photochemical vapor deposition method. It was found that the Al layer serves as seeds to facilitate the p-mu c-Si:H with high crystallinity at an initial growth stage and the Al seeds stimulate the nucleation of Si crystallites. It was also found that the absorption loss in the ultrathin (similar to 50 A) Al-seed layer is negligible in the visible wavelength region due to its natural oxidation. When used in superstrate-type p-i-n amorphous silicon solar cells, even the Al-seeded p-mu c-Si:H film having a several hundred angstrom thickness acts as an excellent p layer compared to the conventional p-mu c-Si:H. (C) 2000 American Institute of Physics. [S0003- 6951(00)03239-3].