Study of formation of boron-rich layers using boron spin-on-dopant diffusion process and its impact on bifacial silicon solar cells

• Main Authors: Chien-Yun Shih, 施芊妘
• Other Authors: I-Chen Chen
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/j722vg

碩士 === 國立中央大學 === 材料科學與工程研究所 === 106 === Most current B diffusion processes used to fabricate n-type solar cell result in the formation of BRL which is located between the borosilicate glass (BSG) and emitter region. The formation of BRL is effective at gettering, but it’s harmful to silicon solar cell performance. The recombination centers in the BRL cause saturation current density degradation, and as the thickness of BRL increases, the contact resistance value increases. Low temperature oxidation and chemical etching are often used to remove the BRL. In this work, we used boron acid as spin-on dopants to form the emitter of n-type bifacial silicon solar cells. We observed the formation of BRL by different concentration boron acid and investigated the influence of removal of the BRL by low temperature oxidation on inverse saturation current density and contact resistivity. We obtained that removing the BRL reduce inverse saturation current density from 1.2x10-11 A/cm2 to 4.5x10-13 A/cm2. In addition, the contact resistance value decreases from 11.06 mΩ-cm2 to 3.97 mΩ-cm2. In order to explore the effects of gradual removal of the BRL in the finished cell, we applied different oxidation conditions to bifacial solar cell. We observed that when the thickness of the BRL decreases, the IQE response increases in the short wavelength. As for the cell performance, it shown that the optimum oxidation condition raised the saturation current density by 4.2 mA/cm2; fill factor by 6.9%; the cell efficiency by 1.7%.