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28th European Photovoltaic Solar Energy Conference and Exhibition; 1545-1547, Strontium silicate (SrSiOx) is one of candidates to be a field effect passivation layer with positive fixed-charges (FCs). In this study, we provide systematic investigations of thermal stability and internal FC state for SrSiOx layer grown on crystalline silicon (c-Si) substrate. The SrSiOx layers were fabricated by growing SrO layers on Si substrates using pulsed laser deposition, and then post-annealing treatment (PAT) in oxygen atmosphere. To investigate the thermal stability of the samples, the PAT was carried out at various temperatures from 500800. From x-ray photoemission spectroscopy measurements, we identified that the SrSiOx/Si structure was maintained after the PAT below 700, but SiOx layer began to grow at the interface above 800. The internal FC state was evaluated by capacitance-voltage (C-V) measurements for samples having various thickness of SrSiOx layer. Negative flat band voltage shift (NFBVS) was observed in the SrSiOx/Si samples annealed at 600 . In the samples with a longer PAT above 2 hours, the effective FC density estimated from the magnitude of the NFBVS was almost constant (1×1012 cm-2) against the thickness variation. From these results, we consider that the origins of the NFBVS would be likely due to intrinsic positive FC existing in the vicinity of the SrSiOx/Si interface. For the interface FC, it is independence from the SrSiOx thickness, and we can freely design FEP layer thickness without constraint. This would provide the degree of freedom in the cell design including anti-refection layers.

28th European Photovoltaic Solar Energy Conference and Exhibition; 4623-4628, By earthquake and tsunami occurred on March 11th 2011, Fukushima nuclear power plant No.1 has generated severe accidents to emit high level radiations and to contaminate foods, water and others with radio isotopes. Such an accidents has given us very important messages such as unclearness for safety and cost effectiveness of nuclear energy and important of clean renewable energies including photovoltaics instead of nuclear energy. This report presents outline of accidents by the Fukushima nuclear power plant and difficulty of further installation of new nuclear power plants in Japan. An idea such as the “Fukushima Solar Village” plan has been proposed to attain employment security, to maintain power supply from those areas to metropolitan cities and to overcome several problems occurred by nuclear power plant accident. Accelerating plan such as further installation of photovoltaic power generation systems in Japan has also been proposed in order to overcome several problems occurred by Fukushima nuclear power plant accident. For realizing accelerating plan, further enhancement of PV R&D is very important and outline of PV R&D Project in Japan is also reviewed. Recent results under such projects are also presented: World record efficiency 44.4% (under 250-300 suns) and 37.9% (under 1-sun AM1.5G) InGaP/GaAs/InGaAs 3-junction solar cells by Sharp, 17.8% CIGS submodules (30x30cm2) by Solar Frontier, 11.9% dye-sensitized solar cell by Sharp, 11.1% organic solar cell by Mitsbishi Chemical and so forth have been demonstrated under the NEDO PV R&D project.

28th European Photovoltaic Solar Energy Conference and Exhibition; 1689-1691, The post deposition hydrogen radical (H•) treatment was employed for aluminum oxide (AlOx) to improve the passivation properties for p-Si. The maximum surface recombination velocity (Smax) at the AlOx/Si interface was significantly improved mainly thanks to the negative fixed charge increase in the AlOx film. The improvement was effective especially for the room temperature deposited AlOx film, therefore we believe the H• treatment has a potential to reduce the production cost.

26th European Photovoltaic Solar Energy Conference and Exhibition; 1920-1922, We evaluate the properties of crystalline defects in silicon substrate fabricated by seeding cast growth. (100) Czochralski silicon was used for the seed crystal. In the region near the seed crystal, 3 twin boundary defects and the SiC precipitates were observed. No particular relationship between twin defects and precipitates were observed. After almost defect free region, the precipitations appeared again and increased their density through the crystal growth procedure. These precipitates were consisted of silicon, carbon, and nitrogen. After the precipitation density increased, the small-angle grain boundaries appeared. Because the precipitation sites appeared, precipitates preferentially occurred at the small-angle grain boundaries. We considered the precipitations consisted from light element atoms such as carbon and nitrogen was one of the major origins of the small-angle grain boundary generation.