Characterization of the Surface Layer on a Strained Si Wafer by Electrochemical Methods

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• 作者：Kaoruho Sakata ; Masahiro Kato ; Nobuhiro Kubo ; Takeshi Senda ; Koji Izunome ; Takayuki Homma
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：March 13, 2008
• 年：2008
• 卷：112
• 期：10
• 页码：3785 - 3788
• 全文大小：202K
• 年卷期：v.112,no.10(March 13, 2008)
• ISSN：1932-7455

文摘

To assess the surface reactivity of strained Si wafers, open circuit potential (ocp) measurement and scanningsurface potential microscopy (SPoM) were carried out. Surface conditions of the wafers were varied by changingthe structure of the wafers, i.e., the Ge content of the SiGe underlayer and the thickness of the strained Silayer. The ocp value of the strained Si was negative compared with that of nonstrained Si, and it shifted inthe negative direction with an increase in Ge content of the SiGe layer and/or in the thickness of the strainedSi layer, indicating that the degree of strain and/or the density of defects at the Si wafer surface affect itsreactivity. In addition, the ocp value shifted in the positive direction to reach the value of the nonstrained Si,possibility due to stress relaxation, when the thickness of strained Si exceeds a certain value, which is expectedto be the "critical" thickness. The SPoM analysis confirmed that the negative potential shift takes place locallyat the surface, whose contrast was associated with the crosshatchlike surface morphology, suggesting thatthere is nanoscopic difference in strain at the strained surface.