The effects of selenium content on Cu(InGa)Se2 thin film solar cells by sputtering from quaternary target with Se-free post annealing

• Published in: Vacuum Vol. 137; pp. 205 - 208
• Main Authors: Zhang, Leng, Zhuang, Daming, Zhao, Ming, Gong, Qianming, Guo, Li, Ouyang, Liangqi, Sun, Rujun, Wei, Yaowei, Zhan, Shilu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2017
• Subjects: CIGS; Quaternary target; Se-free annealing; Quaternary target; CIGS; Se-free annealing
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2016.12.041

Two kinds of Cu(InGa)Se2(CIGS) absorbers and the corresponding solar cells have been fabricated by sputtering from Se-poor and Se-rich quaternary CIGS targets, respectively. The CIGS thin films fabricated by Se-poor target are mainly composed of chalcopyrite CIGS phase together with small amount of Cu2-xSe compound, while the CIGS thin films fabricated by Se-rich target show single chalcopyrite CIGS phase. The electrical properties of Se-poor films are deteriorated severely due to the formation of Cu2-xSe compared with that of Se-rich film. The highest device efficiency of 12.5% has been achieved in the work with absorber sputtering from Se-rich target with Se-free post annealing. It was found that the key limiting factor to success by this method is sufficient selenium in CIGS absorbers.
•The CIGS films were grown by sputtering a Se-rich and Se-poor CIGS quaternary targets.•The annealing is conducted in Se-free inert atmosphere.•The CIGS thin films fabricated by Se-poor target contain small amount of Cu2-xSe compound.•The highest device efficiency of 12.5% has been achieved from Se-rich target.