Development of vertical electrolyte-gated field effect transistors for UV photodetectors

Abstract

Transistor is an element of great importance for electronics, being responsible for functions such as signal amplification and switching. In the context of the electronics alternative to silicon, there is a demand for transistors that can be printed, flexible, transparent, organic or obtained by organic precursors and that can be integrated into smart packaging, ornaments or clothing. In this sense, there is a very recent approach in the literature that aims join two successful configurations, which are: electrolyte-gated transistors and the vertical transistors, resulting in the vertical electrolyte-gated field effect transistors (VEGTs). The combination of the electrolyte with the vertical architecture allows: low leakage current, increasing capacitance, obtaining a nanometer thick channel, biological and radiation sensor applications, good switching speed and reaching transconductance values as high as 814 S/m. The challenge of producing good VEGTs involves the individual study of the three main layers: intermediate electrode, semiconductor and electrolyte. There are many promising materials in this regard and the choice depends on the desired application. For photodetection of ultraviolet radiation (UV), zinc oxide (ZnO) has standing out for the possibility of being obtained from organic precursors that can be processed by solution and deposited by printing. And for deep UV photodetection, gallium oxide (Ga2O3) stands out, which can also be obtained by organic precursors and deposited by printing. As an alternative for carbon-based electrodes, graphene and carbon nanotubes has standing out, and as an alternative for dielectrics, cellulose-based electrolytes has standing out. The purpose of this doctoral project is to develop and study the printed version of VEGTs for UV photodetection, aiming better performance, physical stability, cycling and reproducibility.