A Study on Metallization of N-PERT c-Si Solar Cells by Using Copper Electrochemical Deposition

  • 鍾 羽捷

Student thesis: Master's Thesis


This thesis is mainly using the copper (Cu) electroplating technique to fabricate front electrodes of N-PERT c-Si solar cells With regards to the advantages of Cu electroplating as the metallization process in addition to the low resistivity of Cu it can also be applied to fill high-aspect-ratio structures and its costs is lower than the traditional silver front electrodes by screen printing Therefore the purpose of this thesis is to develop low-cost and high-efficiency solar cells with electroplated Cu front electrodes as alternatives for ones with traditional screen-printed silver front electrode which is limited by its high cost and miniaturized width N-type c-Si solar cells with anti-reflection coatings back electrodes and passivation layer opened by green laser/wet etching are used in this study The stack of front electrodes is copper/nickel where Ni is used as the seed layer/barrier layer and Cu as the conductive layer Owing to the difference in surface structure caused by two different opening methods the electroplating current density and time which would influence the quality of deposition are split in detail One of the important steps in front electrode fabrication is annealing which aims to form NiSix that can improve the adhesion between Si and Ni and also decrease the contact resistance Different annealing time or temperature of solar cell would have different impacts such as gap generation between Ni/Si and the reduction of Voc Solar simulator I-V measurement SEM and TEM analysis are used to investigate the effect of different parameters of electroplating/annealing on the device performance The results show that solar cells with Cu front electrodes demonstrate high efficiency and low contact resistance (ρc) Among all cells opened by wet etching the highest efficiency is 19% and fill factor is about 0 7 Among all cells opened by green laser ablation the highest efficiency is 20 4% fill factor is 0 72 and the contact resistance of all cells is less than 10 mΩcm2 which meets the requirement of current front electrodes The cells opened by laser ablation with the highest efficiency has been analyzed by EDS and the result show that NiSi (atomic ratio about 1:1) is detected which is thought to be beneficial to the electrical properties of the cell In short n-type high efficiency solar cells with electroplated Cu front electrodes are successfully developed
Date of Award2016 Aug 22
Original languageEnglish
SupervisorWen-Shi Lee (Supervisor)

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