Electrolyte-Gated Field-Effect Transistors (EGTs)

A transistor is an electronic device and the most basic building block in modern microelectronics. Typically, transistors are based on silicon and are manufactured in more or less complicated repeatedly photolithographic and chemical process steps. In a simplistic view, the transistor has three terminals (gate, drain, and source) which whom the current flow through the transistor is controlled. The potential on the gate-electrodes defines the amount of free charge carries in the channel, which lies between the drain- and source-electrodes. Depending on the potential between the drain- and source-electrode, a current flows between these two electrodes.

By using novel materials, it is possible to print transistors with conventional printing technologies. This has as benefit that microelectronic circuits can be printed on several substrates (paper, plastic, glass, or silicon). Furthermore, since printing is a digital technique, no masks are required to manufacturing the devices, reducing the manufacturing costs of the applications. Unfortunately, due to the available materials, compatible with the printing process, the performance of printed devices fall back in comparison with silicon based devices. It is worth mentioning, that the goal of printed electronics is not to replace silicon devices, but rather to find its own novel applications, where benefits from the flexible and inexpensive manufacturing processes are expected.

Therefore, in our group we are studying printed electrolyte-gated transistors (EGTs) that are fabricated via inkjet printed. The conductive drain- and source-electrodes are based on lithographic structured indium tin oxide (ITO). However, also printed ITO, silver, and graphene drain- and source-electrodes are evaluated. As semiconductor channel indium oxide (In2O3) is used since it exhibits a high intrinsic mobility, even if printed. The gate-dielectric is comprised by a composite solid polymer electrolyte (CSPE), which establishes a Helmholtz-double layer at the CSPE and In2O3 interfaces. The resulting high capacitance of the Helmholtz-double layer allows to operate the devices at supply voltages around 1 V. A polymer conductor, PEDOT:PSS, is printed on top of the CSPE as gate-electrode.

Within our group we are optimizing the printability of the In2O3 layer to reduce the variability of the devices and to increase the yield of the printed transistors. New device architectures are explored, that can reduce the intrinsic parasitics of the EGTs, hence, increasing the operation speed of the applications. In addition, novel materials are researched that further enhance the performance of the printed applications. In2O3 is an n-type semiconductor, however, in most of the applications complementary p-type transistors are interesting to reduce the leakage currents and therefore the power consumption. For that reason, metal-oxide p-type materials are researched and improved.

Further information:

• Process and Fabrication:
  • Optimizing the Performance of Printed Indium Oxide Thin-Film Transistors Through Gallium Incorporation
  • Electrolyte-Gated Indium Oxide Based Transistor on PET Substrate Enabled by Hybrid Process
  • Wetting Behavior of Inkjet-Printed Electronic Inks on Patterned Substrates
  • Fully Printed Electrolyte-Gated Transistor Formed in a 3D Polymer Reservoir with Laser Printed Drain/Source Electrodes
  • Laser Printed Microelectronics
  • Fabrication and Modeling of pn-Diodes Based on Inkjet Printed Oxide Semiconductors
  • Ink-Jet Printable, Self-Assembled, and Chemically Crosslinked Ion-Gel as Electrolyte for Thin Film, Printable Transistors
  • High Performance Printed Oxide Field-Effect Transistors Processed Using Photonic Curing
• Device Physics and Modeling: 
  • Low-Frequency Noise Characteristics of Inkjet-Printed Electrolyte-Gated Thin-Film Transistors
  • Channel Geometry Scaling Effect in Printed Inorganic Electrolyte-Gated Transistors
  • Nonquasi-Static Capacitance Modeling and Characterization for Printed Inorganic Electrolyte-Gated Transistors in Logic Gates
  • Impact of Intrinsic Capacitances on the Dynamic Performance of Printed Electrolyte-Gated Inorganic Field-Effect Transistors
  • Influence of Humidity on the Performance of Composite Polymer Electrolyte-Gated Field-Effect Transistors and Circuits
  • A Smooth EKV-Based DC Model for Accurate Simulation of Printed Transistors and Their Process Variations
  • From Silicon to Printed Electronics: A Coherent Modeling and Design Flow Approach Based on Printed Electrolyte-Gated FETs
  • Electrolyte-Gated FETs Based on Oxide Semiconductors: Fabrication and Modeling
• Circuit Design:
  • Pass Logic-Gates Based on Electrolyte-Gated Field-Effect Transistors with Metal Oxide Channels
  • Fully Printed Inverters using Metal-Oxide Semiconductor and Graphene Passives on Flexible Substrates
  • Printed Logic Gates Based on Enhancement- and Depletion-Mode Electrolyte-Gated Transistors
  • Progress Report on "From Printed Electrolyte-Gated Metal-Oxide Devices to Circuits"
  • An Inkjet-Printed Low-Voltage Latch Based on Inorganic Electrolyte-Gated Transistors
  • Inkjet-Printed EGFET-Based Physical Unclonable Function - Design, Evaluation and Fabrication
  • Digital Power and Performance Analysis of Inkjet Printed Ring Oscillators Based on Electrolyte-Gated Oxide Electronics
• Integration:
  • Printed 1T1R Arrays for Next-Generation Electronics
• Organic Electronics:
  • Active Matrix-Based Pressure Sensor System with a 4 x 16 Printed Decoder with a Flexible Hybrid Organic Process Design KIT