PhD Defense of KARKER Olfa

                                                                      Tuesday, March 28, 2023 at 2pm

Abstract:
Field-effect transistors based on silicon have been intensely developed over the last years and proved to have major promise in label-free highly sensitive, selective and real-time electrical measurement-based biosensors. However, the lack of chemical inertness and biocompatibility of the silicon material are the two major practical problems that limited the development of FET-based biosensor devices dedicated to long-term in vitro and in vivo biosensor applications. In this regard, silicon carbide (SiC) is an alternative material of choice. SiC could easily challenge Si in the development of FET-based biosensor devices due to its superior electrical and chemical properties combined with biocompatibility and also the compatibility with the Si micromachining techniques. In this thesis, two types of field effect transistors based on SiC have been developed: a core/shell Si/a-SiC nanoribbon FET (Si/a-SiC NRFET) built from Silicon on Insulator (SOI) substrate and an all-SiC open gate junction FET (all-SiC OGJFET). Both types were designed and fabricated through a conventional micromachining top-down approach. The fabrication of the two types was optimized in order to implement a standard process allowing the mass production of the developed devices. The electrical performances of the novel fabricated devices were verified in dry and liquid conditions in view of pH measurement capability as a proof of concept for biosensor applications. Whereas the Si/a-SiC NRFET did not provide a clear pH sensitivity, the all-SiC OGJFET achieved sensitivities up to 495 mV/pH much higher than the Nernst limit (59 mV/pH). This latter high sensitivity is justified by the capacitive coupling between the top and back gates analogically to the SOI-FETs. The hereby proposed all-SiC OGJFET is expected to be also useful for various long-term biosensor applications since it satisfies the typically required performances such as sensitivity and stability.

Jury members :

• Prof.  Daniel ALQUIER, University of Tours (France) : Reviewer
• Prof.   Camelia BALA, University of Bucarest (Romania) : Reviewer
• Prof. Christian BRYLINSKI, University of  Claude Bernard Lyon (France) : Examiner
• Dr.  Marianne WEIDENHAUPT, Grenoble INP – UGA (France) : Examiner
• Prof.  Edwige BANO, Laboratoire de microélectronique électromagnétisme, CNRS, Grenoble (France) : Supervisor
• Dr. Valérie STAMBOULI, Laboratoire des Matériaux et du Génie Physique, CNRS, Grenoble (France) : Co-supervisor 
• Prof. Stephen SADDOW, University of South Florida (United-States) : Guest
• Dr. Konstantinos ZEKENTES, MRG-IESL/FORTH (Greece) : Guest