期刊
NANO LETTERS
卷 11, 期 12, 页码 5574-5580出版社
AMER CHEMICAL SOC
DOI: 10.1021/nl203618h
关键词
Blinking; intermittency; silicon; quantum dot; nanocrystal; photoluminescence; statistical aging; bleaching
类别
资金
- Swedish Research Council (VR)
- research centre LC510 of MSMT
- MSMT [MSM0021620835]
- GAAV [KAN400100701]
The blinking statistics of numerous single silicon quantum dots fabricated by electron-beam lithography, plasma etching, and oxidation have been analyzed. Purely exponential on- and off-time distributions were found consistent with the absence of statistical aging. This is in contrast to blinking reports in the literature where power-law distributions prevail as well as observations of statistical aging in nanocrystal ensembles. A linear increase of the switching frequency with excitation power density indicates a domination of single-photon absorption processes, possibly through a direct transfer of charges to trap states without the need for a bimolecular Auger mechanism. Photoluminescence saturation with increasing excitation is not observed; however, there is a threshold in excitation (coinciding with a mean occupation of one exciton per nanocrystal) where a change from linear to square-root increase occurs. Finally, the statistics of blinking of single quantum dots in terms of average on-time, blinking frequency and blinking amplitude reveal large variations (several orders) without any significant correlation demonstrating the individual microscopic character of each quantum dot.
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