斜向二氧化矽奈米柱次波長結構之抗反射層在矽太陽電池特性改進之研究

我們利用乾式蝕刻(RIE)技術製作一種二氧化矽奈米柱/二氧化矽/二氧化鈦的全方位次波長抗反射層，垂直結構二氧化矽奈米柱之抗反射層的反射率在400 nm到900 nm可以降至10%以下;然而此反射光譜之低反射率分佈之波段不夠平坦，且未完全落在太陽光譜強度較強的波段，所以我們嘗試將奈米柱製作成具傾斜的角度，探討其反射光譜具更寬波段及廣角度抗反射特性。首先，先在單晶矽基板上，蒸鍍了一層59.5 nm的二氧化鈦 (TiO2)與394.5 nm的二氧化矽 (SiO2)，與35 nm的銀(Ag)，以300度持溫兩分鐘進行快速熱退火，使形成銀奈米粒子。接著放置在自製的傾斜角度20、40、60的載台，以RIE通入四氟化碳反映氣體進入腔體進行RIE蝕刻SiO2，蝕刻時間9分鐘可蝕刻掉未保護之 300 nm厚的SiO2，可形成具有傾斜角度的斜向次波長SiO2奈米柱狀結構。經反射率量測，以垂直入射光打在此試片時，其平均反射率在波長範圍400 nm - 950 nm約為7% 左右。其次，所研製出之裸太陽能電池的短路電流密度約為23~24 mA/cm2左右，將裸太陽能電池加上20、40、60斜向次波長結構後，短路電流密度提升至28~29 mA/cm2。最後，我們將太陽能電池放在可變角度之旋轉平台上，使太陽光以不同角度入射，去探討不同傾斜角度之次波長結構，對於不同角度的入射光所造成的影響，進而探討斜向次波長結構抗反射層，對於寬波段、廣角度抗反射效果的可行性。

關鍵字

抗反射層；量子效率；奈米柱；次波長結構；矽太陽能電池

並列摘要

We use an reactive ion etching (RIE) technology to construct the silica (SiO2) Nano-rods on the silica(SiO2)/titanium (TiO2) anti-reflective (AR) coating. The reflectivity of this vertical structure of silica nanorods can be reduced below 10% from 400 nm to 900 nm wavelengths. However, the lowest reflectivity’s location is not at the strongest light intensity band of solar spectrum, and the reflectivity curve is not such flat. So we tried to fabricate oblique nanorods instead of vertical nanorods to research the diversification of reflectivity and the characteristic of Omni-direction anti-reflective. First, we deposited a TiO2 with 59.5 nm, and a SiO2 with 394.5 nm and an 30nm silver film on the silicon solar cell. Then we anneal the silver to gather as the nanoparticles mask. we use RIE with CF4 to etch the top SiO2 to form the nanorods using the oblique 2o, 4o and 6o platform to form different oblique nanorods were obtained. These devices short-circuit current density increases from 23~24 mA/cm2 to 28~29 mA/cm2 were obtained with nomal incident. We change incident light to probe the effect of different oblique angle of Sub-Wavelength structure from 0o to 70o. Finally we probe feasibility of anti-reflective of oblique sub-wavelength structure on the wide angle. From the experimental results, the oblique 4o sub-wavelength structure had wide incident anti-reflective angle characteristics and better than others.

並列關鍵字

Anti-reflection ； Sub-wavelength ； Omni-direction ； Oblique nanorod ； Reflectivity ； EQE ； Si solar cell

參考文獻

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[2]Stephen Y. Chou, Peter R. Krauss, and Preston J. Renstrom, “Imprint Lithography with 25-Nanometer Resolution,”Science, Vol. 272, No. 5258, 1996, pp. 85-87.

[3]C. G. Bernhard and W. H. Miller, “A corneal nipple pattern in insect compound eyes,” Acta Physiol. Scand. Vol. 56, Issue. 3-4, 1962, pp. 385-386.

[4]P. B. Clapham, and M. C. Hutley, “Reduction of lens reflection by moth eye principle,” Nature 244, 1973, pp. 281 – 282.

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國際替代計量

斜向二氧化矽奈米柱次波長結構之抗反射層在矽太陽電池特性改進之研究

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