Intrinsic Microcrystalline Silicon Thin Films Prepared by Hot-Wire Cell Method and Their Application to Solar Cells

概要

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Microcrystalline silicon ($\mu$c-Si:H) thin films and solar cells were prepared by a hot-wire cell (HW-cell) method. A maximum conversion efficiency of 6.0% ($V_{\text{oc}}$: 0.50 V, $J_{\text{sc}}$: 19.69 mA/cm2, F.F.: 0.61, active area: 0.086 cm2, AM1.5) was obtained for $\mu$c-Si:H solar cells prepared at a low filament temperature of 1800°C. The influence of filament temperature on $\mu$c-Si:H film properties was investigated. As a result, it was found from secondary ion mass spectroscopy (SIMS) results that tungsten (W) and aluminum (Al) concentrations largely increase with increasing filament temperature from 1800°C to 2100°C. Next, we found that a considerable degradation of solar cell performances occurs with aging. The degradation of intrinsic $\mu$c-Si:H absorber layers with aging was investigated, and it was found that the peak at 1000–1100 cm-1 originating from Si–O–Si bonds and spin density markedly increase. SIMS results also showed that O and C atoms in our $\mu$c-Si:H films are as low as $2\times 10^{18}$ cm-3 in the initial state and the films can easily undergo post oxidation. However, it was also found that a deposition at a high substrate temperature of more than 165°C is very effective in realizing high-stability $\mu$c-Si:H films and that a 3-μm-thick a-Si:H cap layer can prevent post oxidation.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2004-12-15