Understanding the Electrolyte Background for Biochemical Sensing with Ion-Sensitive Field-Effect Transistors

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• 作者：Alexey Tarasov ; Mathias Wipf ; Ralph L. Stoop ; Kristine Bedner ; Wangyang Fu ; Vitaliy A. Guzenko ; Oren Knopfmacher ; Michel Calame ; Christian Sch枚nenberger
• 刊名：ACS Nano
• 出版年：2012
• 出版时间：October 23, 2012
• 年：2012
• 卷：6
• 期：10
• 页码：9291-9298
• 全文大小：478K
• 年卷期：v.6,no.10(October 23, 2012)
• ISSN：1936-086X

文摘

Silicon nanowire field-effect transistors have attracted substantial interest for various biochemical sensing applications, yet there remains uncertainty concerning their response to changes in the supporting electrolyte concentration. In this study, we use silicon nanowires coated with highly pH-sensitive hafnium oxide (HfO₂) and aluminum oxide (Al₂O₃) to determine their response to variations in KCl concentration at several constant pH values. We observe a nonlinear sensor response as a function of ionic strength, which is independent of the pH value. Our results suggest that the signal is caused by the adsorption of anions (Cl鈥?/sup>) rather than cations (K⁺) on both oxide surfaces. By comparing the data to three well-established models, we have found that none of those can explain the present data set. Finally, we propose a new model which gives excellent quantitative agreement with the data.

Keywords:

nanowire; sensing; anion adsorption; high-k oxide; ion-sensitive field-effect transistor