| Budget Amount *help |
¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2014: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2013: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Outline of Final Research Achievements |
Nonradiative electron transition of the photo excited electron carriers in chalcopyrite CIGS thin films with composition gradient near the buffer and absorption layer were investigate by using our renovated high sensitivity piezoelectric photothermal spectral (PPTS) measurements. Although this compositional gradient is necessary for manufacturing the high efficiency solar cells, we had no experimental methodology to make clear the electronic structures until now. In this project, the effect of the compositional gradient was discussed from both the PPT experiments and theoretical prediction. The observed decrease of the absorption edge was explained by the presence of Cd impurities diffused from the buffer layer during the growth. Since the first approximation model cannot explain the observed experimental results, we found that the carrier diffusion should be taken into account in the heat diffusion equation.
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