期刊
ADVANCED FUNCTIONAL MATERIALS
卷 22, 期 15, 页码 3223-3232出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.201200572
关键词
silicon nanocrystals; interface defects; optical absorption; photothermal deflection spectroscopy; atomistic pseudopotential method
类别
资金
- U.S. Department of Energy Solar Energy Technology Program [DE-AC36-99GO10337]
- DFG [ZA191/27-1, ZA191/24-1]
- U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy [DE-AC36-08-GO28308]
- Center for Advanced Photophysics - an Energy Frontier Research Center
- U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences
The surface of silicon nanocrystals embedded in an oxide matrix can contain numerous interface defects. These defects strongly affect the nanocrystals photoluminescence efficiency and optical absorption. Dangling-bond defects are nearly eliminated by H2 passivation, thus decreasing absorption below the quantum-confined bandgap and enhancing PL efficiency by an order of magnitude. However, there remain numerous other defects seen in absorption by photothermal deflection spectroscopy; these defects cause non-radiative recombination that limits the PL efficiency to <15%. Using atomistic pseudopotential simulations, we attribute these defects to two specific types of distorted bonds: Si-Si and bridging Si-O-Si bonds between two Si atoms at the nanocrystal surface.
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