Large area thin film Si tandem module production using VHF plasma with a ladder-shaped electrode

The use of thin-film silicon for solar cells is a highly promising approach and MHI has developed the world´s largest area deposition technology for a-Si modules with 1.1 m/spl times/1.4 m substrate. Next generation a-Si/ microcrystalline-Si (/spl mu/c-Si) tandem modules have also been developed. 1 m/sup 2/-class large-scale VHF plasma uniformity was confirmed under pressure and frequency conditions of 133 Pa and 60/spl sim/100 MHz for /spl mu/c-Si film deposition. In addition, tandem modules sized 40 cm/spl times/50 cm have been fabricated in our test apparatus as a first step, and initial efficiency of 11.2% for a tandem module (total area of 1800 cm/sup 2/) was obtained. We are targeting tandem module efficiency of 12% by 2003.