| Budget Amount *help |
¥47,450,000 (Direct Cost: ¥36,500,000、Indirect Cost: ¥10,950,000)
Fiscal Year 2012: ¥8,970,000 (Direct Cost: ¥6,900,000、Indirect Cost: ¥2,070,000)
Fiscal Year 2011: ¥8,970,000 (Direct Cost: ¥6,900,000、Indirect Cost: ¥2,070,000)
Fiscal Year 2010: ¥29,510,000 (Direct Cost: ¥22,700,000、Indirect Cost: ¥6,810,000)
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| Research Abstract |
We have studied the epitaxial growth and characteristics of InAs/GaAsSb type-II quantum dot (QD) superlattice and used it to fabricate an intermediate band (IB) solar cell, which is expected to exhibit a high efficiency. First, we have succeeded to observe a clear photocurrent production by 2-step photoabsorption process at room temperature owing to longer carrier lifetimes in type-II QDs. This effect has resulted in an improvement of short-circuit current and efficiency in IB solar cells. Second, we have studied the carrier dynamics in QD structures by ultra-fast optical spectroscopy and clarified the fundamental carrier relaxation process in direct Si-doped QDs. Third, we have studied the optical modes of emission from QD superlattice structure and showed that TM mode starts to increase in proportion to TE mode for a structure with sub-10nm spacing between QD layers indicating a clear formation of QD superlattice miniband, which is required for IB solar cells.
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