This paper reports the survey results on the manufacturing technology trend of thin substrate solar cells for practical use in fiscal 1994. In production of Si raw material, as electron beam melting and ingot production are combined, C, P, Ca and Al are removed by evaporation, while Fe and Ti by solidifying segregation. As the basic technology of continuous casting for substrate production, a drop coagulation method for Si melt is under investigation which is more advantageous in unidirectional solidification and cell conversion efficiency than conventional methods. The cost and future of single crystal Si and polycrystal Si were compared on the basis of document survey. Every institute commonly uses FZ substrates to produce single crystal Si cells, and SiO2 for surface passivation. New cell structure, hetero-structure, thin cell, crystalline defect and lifetime are under investigation for ultrahigh-efficiency solar cells. The technology trend was also surveyed through academic societies and conferences. 5 tabs.
Tatsuta, M 
- New Energy and Industrial Technology Development Organization, Tokyo (Japan)