矽奈米柱陣列太陽電池的製作與建模

Abstract

我們成功利用奈米球微影術(Nanosphere lithography, NSL)搭配金屬輔助化學蝕刻法(metal-assisted chemical etching, MACE)製作出大面積矽奈米柱陣列結構，並從反射率量測中證實矽奈米柱陣列結構具有寬頻譜(broadband)以及廣角度(omnidirectional)的抗反射能力，接著使用嚴格耦合波分析(rigorous coupled wave analysis, RCWA)的方式建立光學模型，且將矽奈米柱陣列應用在厚矽基板與薄矽基板的光學特性進行最佳化；並探討矽奈米柱陣列的增益效果與矽基板厚度的關係；最後將矽奈米柱陣列結構應用於太陽能電池，再利用光電轉換效率以及外部量子效率量測分析，探討矽奈米線陣列結構對元件IV特性的影響，同時亦利用二維電性模擬軟體建立矽奈米柱陣列太陽電池模型，以此研究太陽能電池在不同PN接面輪廓下，擴散長度的變化對元件光電轉換效率的影響；除此之外，我們也模擬了不同表面復合速率對於矽奈米柱陣列的增益效果之影響。由於目前矽奈米柱陣列太陽電池製程難以形成core-shell之PN接面，我們轉而使用乾式蝕刻搭配奈米球微影術這種可精密調控矽奈米柱尺度的方式製作出的矽奈米柱陣列應用在有機/無機異質接面混合太陽電池，並探討其光電元件特性。

We have successfully fabricated large-area silicon nanowire (SiNW) array structures by employing the polystyrene nanosphere lithography and the metal-assisted chemical etching (MACE). Compared to the conventional single-layer antireflective coating (SLARC), SiNW array structures show broadband and omnidirectional antireflection properties in the reflection measurements. Afterward, we use a rigorous coupled wave analysis (RCWA) method to establish the optical model, followed by optical property optimization of SiNWs fabricated on thick and thin silicon substrates. We also explore the relationship between the SiNW enhancement factor and the thickness of silicon substrate. SiNW array structures were made into solar cells, and we analyzed the impact of SiNW array structures on the device current-voltage characteristics through both the power conversion efficiency and external quantum efficiency measurements. Furthermore,the electrical model of SiNW solar cells is established by 2-dimensional electrical simulation software thus we could further study the effect of diffusion lengths on the power conversion efficiency under two different PN junction profiles by simulation. Since it is difficult to achieve core-shell junction profile with silicon nanostructures using industrial manufacturing processes, we turned to fabricating hybrid organic/inorganic heterojunction solar cells and discuss the related photovoltaic device characteristics.