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Out-of-equilibrium body potential measurements on SOI substrates : implementation and applications for biochemical detection

Abstract : In this thesis we propose a new paradigm for biochemical detection based on the out-of-equilibrium body potential in silicon on insulator (SOI) substrates was used in the Ψ-MOSFET configuration. This is typically used for SOI characterization and is an upside-down transistor in which the current though the silicon film is measured by two metallic pressure probes and which is driven by the back gate voltage applied on the bulk of the SOI. The channel is close to the top structure of the SOI, allowing a straightforward influence of any deposited charges on the conduction of the pseudo transistor. The originality of our work resides in the fact that instead of measuring a shift due to charges on the static I-V characteristics, we developed a new method based on the out-of-equilibrium body potential, which appears due to the lack of carriers at the transition between the accumulation and inversion regimes. Charge injection through the metallic probes for channel formation is consequently critical for this effect. Surprisingly, the metal probes on the silicon film show experimentally an ohmic behaviour, which we explained using the emergence of the metallic metastable high pressure phase of silicon by nanoindentation, due to the pressure applied by the pressure probes. Furthermore, we presented a simplified setup for the body potential measurements, which showed a great versatility and stability with regard to the pressure applied on the probes and the position of the probes. The measurements were replicated through TCAD simulations, which ultimately showed that the influence of deposited charges on the silicon film can be measured using this method. Finally, the application of the body potential method for biosensing was realized by an incremental study starting from basic silicon functionalization methods to the detection of DNA. The electric response was proportional to the DNA concentration and a limit of detection of 1µM was estimated from the experimental results. The proof of concept for this new reading method can be implemented to other field-effect devices (i.e. nanowires) and for other biochemical applications.
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Submitted on : Friday, March 27, 2020 - 11:43:33 AM
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  • HAL Id : tel-02521144, version 1



Licinius Pompiliu Benea. Out-of-equilibrium body potential measurements on SOI substrates : implementation and applications for biochemical detection. Micro and nanotechnologies/Microelectronics. Université Grenoble Alpes, 2019. English. ⟨NNT : 2019GREAT052⟩. ⟨tel-02521144⟩



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