Processing development and properties study of parallel-type thin film GaAs solar cells

• Main Authors: Yu-Han Fu, 傅郁涵
• Other Authors: 洪瑞華
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/39759606030409457956

碩士 === 國立中興大學 === 精密工程學系所 === 105 === In this study, the thin film GaAs solar cells were transferred to Ni substrate by epilayer-transferred technique and electroplating. The benefits of this thin film solar cell were the flexible and foldable. In this thesis, the individual solar cell was fabricated and study. Then, the individual thin-film GaAs solar cells were connected in parallel using metal lines by E-gun deposited, and the device performance were investigated. To fabricate tandem thin-film GaAs solar cell, the AuBe/Au layer and electroplated Ni metallic layer were deposited sequentially on GaAs substrate. Then, the GaAs substrate was wet-etched by using NH4OH:H2O2 mixture solution to expose the n-contact ohmic layer. The surface roughness after removing the GaAs substrate were also investigated. After, the n-type electrodes were deposited and anti-reflective layers (TiO2-57.1nm/MgF2-85 nm) were also deposited for improving the conversion efficiency and quantum efficiency. Moreover, to prepare the parallel-type thin film solar cell, the sidewalls of cells were protected by the SiO2. Subsequently, the size of the parallel electrode was defined by standard photolithography. Finally, the bus bars on the solar cells were connected by the metal lines. The efficiencies of thin-film GaAs solar cells and the effect of the anti-reflection layer on the device performance were investigated. The efficiencies of individual solar cell (area size: 0.25 cm2) and the parallel devices with various area sizes (0.25 cm2×2=0.5cm2、0.25 cm2×3=0.75cm2、0.25 cm2×4=1cm2) were analyzed. The efficiency of 0.25 cm2, 0.5 cm2 and 0.75cm2 area sizes are 18.3 %、17.2 %、16.9 % and 15.8 %, respectively. The serial (parallel) resistors of of 0.25 cm2, 0.5 cm2 and 0.75cm2 area size are 24.62 Ω (21.43 KΩ)，30.77 Ω (14.5 KΩ)，60.96Ω (8 KΩ)，42.37Ω (6.8 KΩ, respectively). It was found that the increasing in the series resistance and decreasing in parallel resistance as the area of solar cell increasing resulted from the leakage and bus bar resistance, respectively. Obviously, the passivation of the individual solar cell and metal line connection are the main issues for the parallel solar cells.