高導電率微晶矽氧化物摻雜層應用於薄膜太陽能電池之開發與研究

Abstract

本研究中使用射頻電漿輔助化學氣相沉積系統來沉積微晶矽氧化物薄膜，並應用於矽薄膜太陽能電池。對於單接面非晶矽薄膜太陽能電池而言，吸收層的厚度須薄以減少光劣化效應，因此，必須使用光捕捉效應來增加光程來降低較薄吸收層所造成的吸收限制。微晶矽氧化物薄膜有較大的能隙，較低的吸收係數及較高的電導，適合應用於摻雜層。然而，氧的加入將使薄膜的結晶率與電導同時下降。本研究中藉由調變製程參數，相較於非晶矽n型摻雜層，微晶矽氧化物n型摻雜層可以獲得較大的能隙、較低的折射率及較高的電導。微晶矽氧化物n型摻雜層的特性與透明導電層相似。因此我們將非晶單接面太陽能中的非晶n型摻雜層及透明導電層之背反射結構用非晶n型摻雜層及微晶矽氧化物n型摻雜層代換，本文中最佳的非晶矽單接面太陽能電池之轉換效率為 9.63%，其開路電壓為 890.1 mV，短路電流密度為 14.73 mA/cm2，填充因子為73.51%。此外，我們還使用雙層微晶矽氧化物n型摻雜層取代非晶n型摻雜層及透明導電層之背反射結構，最佳的非晶矽單接面太陽能電池之轉換效率則為 9.60%。

In this study, plasma-enhanced chemical vapor deposition (PECVD) was used to deposit hydrogenated microcrystalline silicon oxide (μc-SiOx:H) for thin-film solar cell applications. In hydrogenated amorphous silicon (a-Si:H) single-junction thin film solar cells, the thickness of the absorber layer should be thin to reduce Staebler-Wronski effect. The light trapping is necessary to achieve longer light paths to reduce the limit of the light absorption due to thinner absorber. The μc-SiOx:H with wider bandgap, lower coefficient and higher conductivity was a suitable doped layer. However, the incorporation of oxygen decreased the crystallinity as well as the conductivity. In this study, by optimizing the deposition conditions, the μc-SiOx:H film with the higher bandgap, higher conductivity and lower refractive index than that of a-Si:H was obtained. The characteristics of μc-SiOx:H n-layer was found to be similar to transparent conductive oxide (TCO). Thus, we replaced the a-Si:H(n)/TCO back reflector by a-Si:H(n)/μc-SiOx:H(n)/TCO in a-Si:H single-junction solar cell. The highest efficiency of the a-Si:H single-junction solar cell was 9.63 % with Voc = 890.1 mV, Jsc = 14.73 mA/cm2 and F.F. = 73.51%. Besides, µc-SiOx:H(n)/µc-SiOy:H(n)/Ag structure was used to replace a-Si:H(n)/TCO/Ag as back reflector (BR) structure and the best conversion efficiency in this study was 9.60%.