Boron Doped Solid Phase Epitaxy on Mono-Crystalline Si for BSF and n-type emitter fabrication in Solar Cells by Aluminum-Induced Crystallization

• Main Authors: Lin, Hung-Hsi, 林泓希
• Other Authors: 蔡春鴻
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/97589927710985217762

碩士 === 國立清華大學 === 工程與系統科學系 === 99 === The Back-Surface-Field structure is usually fabricated by screen-printing technology, and the emitter is produced by ion implantation or diffusion in solar cell. Although all of these methods obtain continuous and high carrier concentration p-type silicon film, the processes must undergo a heat treatment above 800oC. It causes some critical issues such as thermal budget problem and residual strain energy results from different thermal expansion coefficient between silicon and aluminum. In this research, we produced a continuous and p-type silicon film by aluminum induced crystallization (AIC) process to work as BSF or emitter. The advantages that fabricating p-type silicon film by AIC is the low temperature process. However, the carrier concentration obtained by AIC is only 3x1018cm-3 which is lower than other methods. It must surpass 1019cm-3, or the efficiency would decrease because of reduction of carrier lifetime caused by low carrier concentration. We co-sputter with boron into aluminum film at first, and then boron atoms dissolve into silicon and provide holes after AIC process completes. It results in increase of carrier concentration while the annealing temperature keeps the same at 400oC. We expect the technology that produces high carrier concentration silicon film at low temperature can be used as BSF and emitter, and then gets better performance compared to conventional AIC process.