Fabrications of Si thin-film solar cells by hot-wire chemical vapor deposition and laser doping techniques

In this paper, we report a novel low-temperature process for fabricating a Si thin-film solar cell on a glass substrate. The cell structure was composed of glass/Al/p-i-n Si/Ag (grid), where the Si intrinsic layer was deposited by hot-wire chemical vapor deposition. All the doped Si layers were produced using a postgrowth laser-doping process. The hot-wire-deposited amorphous, macrocrystalline and polycrystalline Si films showed significant differences in band gap and structural properties as determined by Raman spectroscopy, spectral optical transmission measurements, and transmission electron microscopy. The corresponding crystalline volume fractions were 93, 73, and 12%, respectively. It was found that the best solar cells were fabricated with a Si intrinsic layer deposited at the transition from microcrystalline to polycrystalline regimes. A preliminary efficiency of 1.9% was obtained for an n-i-p structured solar cell on an untextured glass substrate.