José Alexandre Diniz
State University of Campinas (UNICAMP)
ISFET (Ion Sensitive Field Effect Transistor)
The big difference between an ISFET (Ion Sensitive Field Effect Transistor) and a conventional MOSFET (Metal Oxide Semiconductor FET) is the absence of the upper electrode on the gate oxide of the device. In the case of an ISFET, the gate reference electrode with the solution (of chemical or biological materials), which is in contact with the gate oxide (dielectric), works as the upper electrode, inducing the channel in the semiconductor and enabling the conduction of electric current between source and drain terminals. On these two terminals, there are polymer layers that serve as a barrier against chemical or biological solutions. Therefore, the choice of the gate oxide is of great importance, since it must present chemical stability when in contact with the solution that will be measured. The solution pH is the primary parameter measured. The gate dielectric chosen for application as a pH sensor must perform measurements in acidic and basic media and form hydroxyl and hydrogen bonds. This ability is associated with highly electronegative atoms, such as fluorine, oxygen, and nitrogen.
Furthermore, ISFETs can detect water contamination metals, DNA, RNA, enzymatic, antigen-antibody, and cell-related targets. Thus, thin films of SiNx, TiOx, TaOx, AlOx, and AlN were chosen as gate dielectrics because they are compatible with chemical or biological substances. Various results from the literature will be presented in this invited talk.
Also, it will be shown that ISFET devices are essential sensors for future instrumentation, as they enable the detection of various chemical and biological species, using different materials as gate dielectrics, electrodes, and conduction channels.
José Alexandre Diniz holds a degree in Physics, a master’s degree, and a doctorate in Electrical Engineering from the State University of Campinas (Unicamp), obtained in 1988, 1992, and 1996, respectively. He completed his postdoctoral studies from 1996 to 1998 in the Department of Semiconductors, Instruments, and Photonics (DSIF) of the Faculty of Electrical and Computer Engineering (FEEC) at Unicamp, supported by a FAPESP scholarship. In January 1998, he undertook a visiting researcher internship at the University of Florida in Gainesville, FL, USA. He was a PQ researcher at Unicamp’s Center for Semiconductor Components and Nanotechnologies (CCSNano) from 1999 to 2002. Since 2002, he has been a professor at FEEC/Unicamp in the area of electronics, serving as an associate professor from July 2007 to April 2017 and currently as a full professor. His research continues at CCSNano, where he served as Associate Director from 2005 to 2010 and as Director from 2010 to 2016. He was Vice President of the Brazilian Microelectronics Society (SBMicro) from 2016 to 2020. He was the director of FEEC/Unicamp from May 2019 to April 2023. He has published over 210 articles in indexed journals and international conferences. He has supervised 20 doctoral and 21 master’s students. Prof. Diniz is a CNPq Research Productivity Fellow – Level 1C. He has experience in Microelectronics, with an emphasis on Micro and Nano fabrication based on MOS, MEMS, HBT, and graphene technologies. Due to his contributions in the field, he received the 2022 Father Landell de Moura Award, promoted by the Brazilian Society of Microelectronics (SBMicro), and the 2024 Zeferino Vaz Award for academic recognition, promoted by Unicamp.