Characterization of Self-Assembled Organic Films Using Differential Charging in X-ray Photoelectron Spectroscopy

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• 作者：Manish Dubey ; Irina Gouzman ; Steven L. Bernasek ; and Jeffrey Schwartz
• 刊名：Langmuir
• 出版年：2006
• 出版时间：May 9, 2006
• 年：2006
• 卷：22
• 期：10
• 页码：4649 - 4653
• 全文大小：102K
• 年卷期：v.22,no.10(May 9, 2006)
• ISSN：1520-5827

文摘

Differential charging is often regarded as a problem in X-ray photoelectron spectroscopic studies, especially forinsulating or partially conducting samples. Application of a positive bias can reduce the effect of differential chargingby attracting stray electrons from the system, thereby compensating for the electron loss. On the other hand, differentialcharging effect can be enhanced by the application of a negative bias to the sample during spectrum acquisition. Thesuccessful use of the differential charging technique to distinguish between multi- and monolayer organophosphonatefilms on oxide-covered silicon has been reported. A detailed description of this technique is now presented whichshows how differential charging can be used as an important tool for the characterization of self-assembled filmsdeposited on various surfaces. The dependence of this technique on the conductivity of the substrate has been investigatedby studying the spectral behavior of the deposited films of phosphonic acid on conducting, semiconducting, andinsulating samples (stainless steel, silicon, and glass). Application of either positive or negative dc electrical bias affectsthe carbon core-level (C1s) line shape and intensity, which is dependent on the atom's physical location above thesurface.