Chemical and electrical passivation of single-crystal silicon(100) surfaces through a two-step chlorination/alkylation process
Chemical and electrical passivation of single-crystal silicon(100) surfaces through a two-step chlorination/alkylation process
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DOI：
10.1021/jp056773x
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发表时间：
2006-08-03
影响因子：
3.3
通讯作者：
Lewis, Nathan S.
中科院分区：
文献类型：
--
作者：
Nemanick, E. Joseph;Hurley, Patrick T.;Lewis, Nathan S.
用两步自由基氯化-格氏(R=MgCl，R=CH3，C2H5，C4H9，C6H5或CH2C6H5)烷基化方法对单晶Si(100)表面进行了功能化处理。烷基化后，X-射线光电子能谱(XPS)没有检测到表面的氯，C1S区出现了硅诱导的峰移动，表明是Si-C键。不出所料，随着烷基的空间体积增加，这一峰的相对强度减小。尽管Si(100)表面的顶位没有完全的烷基封端，但与端氢的Si(100)表面相比，功能化显著降低了表面在空气中的氧化速率，在空气中暴露一个多月后，烷基化表面形成的氧化物不到半个单分子层。用射频光电导衰减法对载流子寿命的研究表明，甲基化表面的表面复合速度为-lt；30 cm S(-1)，其他烷基功能化的硅表面的复合速度为-lt；60 cm S-1。软X射线光电子能谱分析表明，H-Si(100)表面主要由SiH、SiH2和SiH3物种封端，而Cl-Si(100)表面主要由一氯(SiCl2和SiHCl)和二氯(SiCl2和SiHCl2)硅物种封端。甲基化产生的信号与由SiH-(CH3)-、SiH2(CH3)-和Si(CH3)(2)类物种产生的硅烷基键终止一致。
Single-crystal Si(100) surfaces have been functionalized by using a two-step radical chlorination-Grignard (R = MgCl, R = CH3, C2H5, C4H9, C6H5, or CH2C6H5) alkylation method. After alkylation, no chlorine was detectable on the surface by X-ray photoelectron spectroscopy (XPS), and the C 1s region showed a silicon-induced peak shift indicative of a Si-C bond. The relative intensity of this peak decreased, as expected, as the steric bulk of the alkyl increased. Despite the lack of full alkyl termination of the atop sites of the Si(100) surface, functionalization significantly reduced the rate of surface oxidation in air compared to that of the H-terminated Si(100) surface, with alkylated surfaces forming less than half a monolayer of oxide after over one month of exposure to air. Studies of the charge-carrier lifetime with rf photoconductivity decay methods indicated a surface recombination velocity of < 30 cm s(-1) for methylated surfaces, and < 60 cm s-1 for Si surfaces functionalized with the other alkyl groups evaluated. Soft X-ray photoelectron spectroscopic data indicated that the H-Si(100) surfaces were terminated by SiH, SiH2, and SiH3 species, whereas Cl-Si(100) surfaces were predominantly terminated by monochloro (SiCl and SiHCl) and dichloro (SiCl2 and SiHCl2) Si species. Methylation produced signals consistent with termination by Si-alkyl bonding arising from SiH-(CH3)-, SiH2(CH3)-, and Si(CH3)(2)-type species.