Development of Large Bandgap and Highly Conductive N-Type μc-SiOX:H as Back Reflecting Layer for Silicon Thin-Film Solar Cells

• Main Authors: Tsai ,Yuan-Feng, 蔡沅夆
• Other Authors: Tsai, Chuang-Chuang
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/7eer6s

碩士 === 國立交通大學 === 光電工程研究所 === 102 === In this thesis, large bandgap and highly conductive N-type μc-SiOX as the back reflecting (BR) layer for silicon (Si) thin-film solar cells has been investigated. The Si thin-film solar cells were prepared by the 27.12 MHz radio-frequency plasma-enhanced chemical vapor deposition (PECVD) system. The requirements of μc-SiOX:H(n) as the BR layer was low refractive index and acceptable conductivity. To meet the requirements of a back reflecting layer, the methods to adjust the oxygen content of μc-SiOX:H(n) such as varying CO2-to-SiH4 flow ratio, H2 dilution, RF power and pressure of PECVD process were executed. We also applied the optimized μc-SiOX:H(n) to the μc-Si:H single-junction solar cells. In addition, the different back reflectors applied to the μc-Si:H solar cells were compared. By using μc-SiOX:H(n) as a replacement for both an n-layer and ITO, higher quantum efficiency (QE) and cell efficiency at the long wavelength were obtained. Meanwhile, the process can be simplified. We applied this BR not only to the single-junction solar cells but also the tandem and triple-junction solar cells. Similar trend of higher QE at the long wavelength was found in multi-junction solar cells. With optimized μc-SiOX:H(n), we obtained the optimal efficiency of 10.63 % in a-Si:H/μc-Si:H tandem solar cell, with short-circuit current density (JSC) = 10.36 mA/cm2, open-circuit voltage (VOC) = 1.36 V and Fill factor (FF) = 75.18%. The cell efficiency of 8.93 % was obtained in a-Si:H/a-Si1-YGeY:H/μc-Si:H triple-junction solar cell, with JSC = 6.31 mA/cm2, VOC = 1.98 V and FF = 71.52 %.