Recombination of photo-generated charge carriers in H-terminated and (photo-)oxidized silicon nanoparticles
Recombination of photo-generated charge carriers in H-terminated and (photo-)oxidized silicon nanoparticles
复制标题
H 封端和（光）氧化硅纳米粒子中光生电荷载流子的重组
DOI：
10.1016/j.apmt.2021.101071
复制
发表时间：
2021
影响因子：
8.3
通讯作者：
R. Pereira
中科院分区：
文献类型：
--
作者：
B. Falcão;J. Leitão;L. Ricardo;H. Águas;R. Martins;R. Pereira
在硅纳米晶体、量子点或纳米颗粒（Si-NPs）中，光生载流子的重组机制和发光的起源对于这些材料在未来纳米光电子学中的应用至关重要。在过去的二十年里，这些问题在文献中进行了激烈的辩论，不同的调查报告了看似矛盾的结果。通过本文的研究，我们阐明了具有不同表面钝化形式（即h端化和（光）氧化）的Si-NPs中主要的电子-空穴复合机制和发光的来源。我们发现，与表面钝化无关，在低激发功率下，光载流子的重组主要是通过缺陷态进行的单分子通道重组，而在相对高的激发下，电子-空穴的双分子重组占主导地位。此外，我们确定了在h端Si-NPs中，发光主要是由于NPs的Si核的子带隙电子态的重组，而在表面（光）氧化的Si-NPs中，可以观察到双组分发光，分别来自Si核和氧化相关态。此外，我们讨论了即使在低氧和水分子环境下，h端Si-NP对光氧化的临界敏感性及其对Si-NP应用的影响。光氧化是在Cabrera-Mott化学反应理论中描述的。
The mechanisms of recombination of photo-generated charge carriers and the origin of luminescence in silicon nanocrystals, quantum dots or nanoparticles (Si-NPs) are essential for the application of these materials in future nano-optoelectronics. In the last two decades, these issues have been lively debated in the literature, with different investigations reporting seemingly contradicting results. With the study presented here, we clarify the dominant electron-hole recombination mechanisms and the origin of light emission in Si-NPs with different forms of surface passivation, namely H-terminated and (photo-)oxidized. We find that, independently of surface passivation, at low excitation powers recombination of photo-carriers is dominated by monomolecular channels via defect states, while at relatively high excitation electron-hole bimolecular recombination dominates. Moreover, we establish that in H-terminated Si-NPs, light emission is mainly due to recombination involving sub-band gap electronic states at the Si core of the NPs, whereas in surface (photo-)oxidized Si-NPs a two-component luminescence is observed, originating from Si core and oxide-related states, respectively. Further, we discuss the critical sensitivity of H-terminated Si-NPs to photo-oxidation even under low oxygen and water molecule environment and its consequences for Si-NP applications. Photo-oxidation is described within the Cabrera-Mott chemical reactions theory.
影响因子：
3.7
作者：
Hartel, A. M.;Gutsch, S.;Zacharias, M.
通讯作者：
Zacharias, M.
影响因子：
3.7
作者：
Hartel, A. M.;Gutsch, S.;Zacharias, M.
通讯作者：
Zacharias, M.