decrease the weight of cell, the thickness of Si wafer is going to be lessened from 200-50 gm (7). Radiation damage is found to be decreased by doping B or by decreasing O content (8). Furthermore, as the material which suffers less damage by radiation and enables higher conversion efficiency, InP has been studied in addition to GaAs. Less than 20% of efficiency degradation after fluenced by 101K gammaphotons per square centimeters was reported (9). As for low cost technology, large area cell (2x2, 2x4 to 5x5 cm2) and improved interconnection are now being studied (10). The single crystalline Si solar cell shows an efficiency up to 15%, while the GaAs tandem cell is said to approach 25-30%. An ultra-thin GaAs epitaxial cell which has a thickness of about 10 /z has been reported (11). A quite unique attempt to pursue 50% efficiency is being investigated. The concept of the "Plasmon” cell consists of the conversion of solar radiation energy over a full range of spectrum into electron surface waves on metal and power extraction through nonelastic tunneling pn junction (12). CONCLUSION Terrestrial and space-use solar cell technology apparently seem to grow separately. But there is a close influence that is hidden between them. Foremost technologies created in space-use solar cell have hitherto improved the terrestrial cell. But in the future, the reverse influence, namely, the introduction of mass production technology to space-use cell manufacturing, the application of evaluation methods of terrestrial solar cell and the realization of ultimate low cost cell by using innovative terrestrial solar cell technology will appear according to the establishment of solar cell industry background. REFERENCES 1. S. Hayashi, A. Onoe, and T. Kato, Photovoltaic Industry and Possible Seeds for SPS Solar Cells, Proc. 1st ISAS Space Energy Symp., 83-88, 1982. 2. National Photovoltaic Program, Five Year Research Plan, Dept, of Energy. 3. P.D. Maycock, Overview-Cost Goals in the LSA Project, 14th IEEE Photovoltaic Specialist Conf., pp. 6-12, San Diego, CA, 1980. 4. J.B. Milstein, R. W. Hardy, and Y.S. Tsuo, Research on Polycrystalline Silicon Solar Cells: Goals and Accomplishments, 16th IEEE Photovoltaic Specialist Conf., pp. 119-122, San Diego, CA, 1982. 5. Y. Maeda, T. Yokoyama, and I. Hide, Large Area Silicon Sheet Produced by the Spinning Method, pp. 133-136, ibid., 1982. 6. K. Yamagami, S. Noguchi, K. Kurokawa, and T. Horigome, Conceptual Design of a 500 kW/Year Mass-Production Process of Low-Cost Silicon Solar Cell and Module, Internal. Solar Energy Soc., Solar World Forum, Brighton, England, E1A-1, 1981. 7. F. Ho and P.A. Iles, Recent Advances in Thin Silicon Solar Cells, 16th IEEE Photovoltaic Specialist Conf., pp. 156-159, Orlando, FL, 1982. 8. J.P. Mullin and D.J. Flood, NASA Space Photovoltaic Research and Technology Programs, Proc. 3rd Europ. Symp. Photovoltaic Generators in Space, pp. 121-126, Bath, England, 1982. 9. A. Yamamoto, M. Yamaguchi, and C. Uemura, High Conversion Efficiency and High Radiation Resistance InP Homojunction Solar Cells, Appl. Phys. Lett. 44, 611-613, 1984. 10. K.W. Matthei, D.K. Zemmrich, and M. Webb, Optimization of Large Area Solar Cells for Low Cost Space Application, 15th IEEE Photovoltaic Specialist Conf., pp. 228-234, Orlando, FL, 1981. 11. R.J. Boettcher, P.G. Borden, and M.J. Ludowise, Ultrathin GaAs and AlGaAs Solar Cells, 16th IEEE Photovoltaic Specialist Conf., pp. 1470-1473, San Diego, CA, 1982. 12. L.M. Anderson, Parallel-Processing with Surface Plasmons, a New Strategy for Converting the Broad Solar Spectrum, pp. 371-377, ibid., 1982. 13. Y. Hamakawa, Jarect, Vol. 6, Amorphous Semiconductor Technologies & Devices, pp. 1-8, Ohmsha Ltd., Japan, 1983. 14. H.W. Brandhorst and J.C.C. Fan, The Solar Electricity Future (Panel Discussion), 16th IEEE Photovoltaic Specialist Conf., pp. 1478-1484, San Diego, CA, 1982. 15. Dept, of Energy Summary Report, DOE/ER-0035, p. 14, 3 Feb, 1975.
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