Measurement of the Surface Recombination Velocity in Organically Functionalized Silicon Nanostructures: The Case of Silicon on Insulator

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• 作者：Romain Coustel ; Quentin Beno卯t 脿 la Guillaume ; Vincent Calvo ; Olivier Renault ; Lionel Dubois ; Florence Duclairoir ; Nicolas Pauc
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：November 17, 2011
• 年：2011
• 卷：115
• 期：45
• 页码：22265-22270
• 全文大小：869K
• 年卷期：v.115,no.45(November 17, 2011)
• ISSN：1932-7455

文摘

As an alternative to the traditional surface oxidation of silicon into SiO₂, covalently bonded organic monolayer is investigated as a mean to electronically passivate silicon surfaces and applied to the particular case of 2D silicon wells made on silicon on insulator. Functionalization of the silicon surface with a C₁₁-alkyl (Si鈥揅₁₁) chain is achieved and confirmed by X-ray photoelectron spectroscopy (XPS). We use a direct detection of the photoluminescence decay rate of the free carriers generated into the 2D silicon crystal (thickness in the 90鈥?00 nm range) as a marker of the surface quality and find a Si鈥揅₁₁ surface recombination velocity of 61.6 卤 0.9 cm s^鈥?. This type of measurement on such a type of modified Si samples is original and confirms that low surface recombination velocity can be reached when an organic layer is used, illustrating the fact that such a technique is an interesting passivation method. Comparison with hydrogenated Si (Si鈥揌) surface is done. Freshly prepared Si鈥揌 surfaces show a better recombination velocity (22.5 卤 0.4 cm s^鈥?) than the Si鈥揅₁₁ surface, but sample aging reverses such a trend. As confirmed by XPS, organic monolayer slows down native silica, and hence carrier trap formation, demonstrating that covalently grafted organic monolayers on Si exhibit satisfying electronic and chemical passivating properties.