利用漸變氮化矽結合次波長結構應用在三五族三接面太陽能電池上之全波段抗反射層研究

Abstract

在本論文中，研究不同抗反射層結構運用在三五族三接面太陽能電池上來提升太陽能電池效率。又以漸變氮化矽結合次波長結構運用在三接面三五族太陽能電池上最俱有影響力，此結構俱有全波段的低反射率。在製作漸變氮化矽結構的方式，首先，藉由調變SiH4/N2 的流量來沈積SiNx抗反射層，接著利用奈米金粒子作為蝕刻抵擋層，進而使用漸變的氮化矽次波長抗反射層結構運用在三接面三五族太陽能電池上。藉由利用Finite-Difference Time-Domain(FDTD) solutions 此軟體，經由模擬分析結果，可得知最佳化次波長結構的深寬比，並將此結果應用在磷化銦鎵/砷化鎵/鍺三接面太陽能電池。為了得到高深寬比的次波長結構，利用濺鍍的方式鍍上一層極薄的金薄膜，並利用快速熱退火的方式得到金耐米粒子以作為蝕刻的光罩抵擋層。並利用感應耦合式電漿蝕刻機調變製程參數進行非等向性蝕刻製作次波長結構，進而達到在寬頻譜具有低反射率的抗反射層，最後，成功製作出具有次波長結構的漸變氮化矽抗反射層三接面太陽能電池。此外，相較於沒有抗反射層以及傳統利用75奈米氮化矽作為抗反射層的太陽能電池元件而言，光電轉換效率分別提升了4.4% 以及1.2%。更進一步，量測反射率以及外部量子效率，分別達到全波段反射率小於6%，以及外部量子效率達到 85％。

In this research, we investigated the effect of different anti-reflective coating (ARC) layers on the enhancement of III-V multi-junction solar cell’s efficiency, and found that the sub-wavelength structures (SWS) combined with the graded SiNx are an efficient way to reduce the light reflection on the Ga0.5In0.5P/GaAs/Ge triple-junction solar cell. First, we modulated the SiH4/N2 ratio and deposited the graded SiNx by PECVD. Then, we used Finite-Difference Time-Domain (FDTD) solutions to simulate and optimize the SWS aspect ratio. In order to fabricate such high aspect ratio, the ultra thin gold film deposited by sputter was annealed to form the gold nanoparticles as the etching mask, and then the SWS was formed by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). Finally, InGaP/InGaAs/Ge triple-junction solar cells with graded SWS-SiNx ARC were successfully fabricated. In the other hand, the SWS anti-reflective coating shows a broadband spectral response of reflection characteristics. Besides, compared to solar cells without ARC and with conventional single layer ARC, the conversion efficiency of the SWS-SiNx ARC is enhanced by 4.4% and 1.2%, respectively. Moreover, the reflectance is smaller than < 6% in the broadband, and the external quantum efficiency measurement can achieve 85 %.