The “Micromorph” cell: a new way to high-efficiency-low-temperature crystalline silicon thin-film cell manufacturing?

Hydrogenated microcrystalline Silicon (µc-Si:H) produced by the VHF-GD (Very High Frequency Glow Discharge) process can be considered to be a new base material for thin-film crystalline silicon solar cells. The most striking feature of such cells, in contrast to conventional amorphous silicon technology, is their stability under light-soaking. With respect to crystalline silicon technology, their most striking advantage is their low process temperature (220 °C). The so called “micromorph” cell contains such a µc-Si:H based cell as bottom cell, whereas the top-cell consists of amorphous silicon. A stable efficiency of 10.7% (confirmed by ISE Freiburg) is reported in this paper. At present, all solar cell concepts based on thin-film crystalline silicon have a common problem to overcome: namely, too long manufacturing times. In order to help in solving this problem for the particular case of plasma-deposited µc-Si:H, results on combined argon/hydrogen dilution of the feedgas (silane) are presented. It is shown that rates as high as 9.4 Å/s can be obtained: furthermore, a first solar cell deposited with 8.7 Å/s resulted in an efficiency of 3.1%

which should be used for any reference to this work 1 The "Micromorph " cell: a New Way to High- Efficiency-Low-Temperature Crystalline Silicon

Abstract. Hydrogenated microcrystalline Silicon (µc-Si:H) produced by the VHF-GD (Very High Frequency Glow Discharge) process can be considered to be a new base material for thin-film crystalline silicon solar cells. The most striking feature of such cells, in contrast to conventional amorphous silicon technology, is their stability under lightsoaking. With respect to crystalline silicon technology, their most striking advantage is their low process temperature (220°C). The so called "micromorph " cell contains such a µc-Si:H based cell as bottom cell, whereas the top-cell consists of amorphous silicon. A stable efficiency of 10.7 % (confirmed by ISE Freiburg) is reported in this paper. At present, all solar cell concepts based on thin-film crystalline silicon have a common problem to overcome: namely, too long manufacturing times. In order to help in solving this problem for the particular case of plasma-deposited µc-Si:H, results on combined argon /hydrogen dilution of the feedgas (silane) are presented. It is shown that rates as high as 9.4 Å/s can be obtained; furthermore, a first solar cell deposited with 8.7 Å/s resulted in an efficiency of 3.1%. 1