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| Author(s): |
Carlos Augusto Bergfeld Mori
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2023-09-26 |
| Examining board members: |
João Antonio Martino;
Sara Dereste dos Santos Perseghini;
Sebastião Gomes dos Santos Filho;
Victor Sonnenberg
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| Advisor: | João Antonio Martino; Paula Ghedini Der Agopian |
| Abstract | |
Biosensors play a fundamental role on the improvement of life expectancy and its quality in a society, being extremely important to monitor in real time the development of diseases and even to prevent high-risk biological threats. This doctoral thesis proposes for the first time the fabrication, electrical characterization, and application as a biosensor of a new device, a back-enhanced Silicon-On-Insulator tunneling fieldeffect transistor (BESOI Tunnel-FET). First, simulations are performed, which verify the viability of the proposed structure, showing that it can operate as a p-type channel Tunnel-FET or an n-type channel MOSFET, depending only on the voltages applied. From the characteristics and behaviors observed during simulations, the work proceeds to the fabrication of the devices, using a set of masks specifically designed for this project, resulting in 290 m long and 210 m wide transistors, with an oxide thickness of 10 nm. Next, their electrical characterization is performed, resulting in currents of hundreds of microamperes, with threshold voltage varying from 2 V to -2 V, depending on the substrate bias, and subthreshold swing of approximately 100 mV/dec for the nMOS operation. While functioning as a pTFET, currents of hundreds of nanoamperes are observed, with the highlight that theres no parasitic ambipolar effect, usually present in tunnel effect transistors. Besides that, tests of its application as a biosensor are performed, showing a linear relation between glucose concentration and drain current. Finally, results of the studies regarding the noise in bioFETs, that is, modified finFETs without gate metal with their exposed oxide surfaces functionalized for operation as biosensors, fabricated at imec, Belgium, are presented, having as main result a maximal signal to noise ratio of approximately five times when the devices gates are biased around the threshold voltage, enabling their application as biosensors capable of detecting specific DNA molecules. (AU) | |
| FAPESP's process: | 17/26489-7 - Project and fabrication of a BE SOI Tunnel-FET as biosensitive element |
| Grantee: | Carlos Augusto Bergfeld Mori |
| Support Opportunities: | Scholarships in Brazil - Doctorate |