Time-correlated single-photon counting study of multiple photoluminescence lifetime components of silicon nanoclusters
Time-correlated single-photon counting study of multiple photoluminescence lifetime components of silicon nanoclusters
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DOI：
10.1016/j.jlumin.2012.10.038
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发表时间：
2013-04
影响因子：
3.6
通讯作者：
D. Diamare;M. Wojdak;S. Lettieri;A. Kenyon
中科院分区：
文献类型：
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作者：
D. Diamare;M. Wojdak;S. Lettieri;A. Kenyon
我们报告的时间分辨的光致发光测量的二氧化硅含有硅纳米团簇（Si NC），通过PECVD和退火温度在700°C和1150°C之间的薄膜。虽然硅纳米碳的近红外发射已经研究了很长时间，但可见光发射由于其非常短的衰减时间和最近报道的随着纳米碳尺寸减小的红移而最近才引起人们的兴趣。我们用时间相关单光子计数法分析了450- 700 nm范围内皮秒时间分辨率的光致发光衰减动力学。在由此产生的多指数衰减中，可以清楚地区分出两个主要成分：一个非常短的成分，在数百皮秒的范围内，和一个纳秒成分。在这个波长范围内，我们没有检测到微秒组件通常与激子复合。我们将纳秒分量与缺陷弛豫相关联：它在较高温度下退火的样品中的强度降低，这表明缺陷的贡献随着温度的升高而降低。还讨论了非常快的PL分量（ps时间区域）的起源。我们发现，这是一致的多激子的俄歇复合时间。进一步的工作需要做，以评估俄歇控制的重组的光致发光的缺陷辅助机制的贡献。
We report time-resolved photoluminescence measurements of thin films of silica containing silicon nanoclusters (Si NCs), produced by PECVD and annealed at temperatures between 700°C and 1150°C. While the near infrared emission of Si NCs has long been studied, visible light emission has only recently attracted interest due to its very short decay times and its recently-reported redshift with decreasing NCs size. We analyse the PL decay dynamics in the range 450–700nm with picosecond time resolution using Time Correlated Single Photon Counting. In the resultant multi-exponential decays two dominant components can clearly be distinguished: a very short component, in the range of hundreds of picoseconds, and a nanosecond component. In this wavelength range we do not detect the microsecond component generally associated with excitonic recombination. We associate the nanosecond component to defect relaxation: it decreases in intensity in the sample annealed at higher temperature, suggesting that the contribution from defects decreases with increasing temperature. The origin of the very fast PL component (ps time region) is also discussed. We show that it is consistent with the Auger recombination times of multiple excitons. Further work needs to be done in order to assess the contribution of the Auger-controlled recombinations to the defect-assisted mechanism of photoluminescence.