Electrolyte-Gated Oxide Transistors by Ink-jet Printing
Printed electronics is a rapidly developing field of research that involves solution processing and covers a broad range of research activities, starting from a basic field-effect transistor to complex logics, memories, lighting, photovoltaics and sensors.
Printed logics is the most complex and intriguing part of it. In order to fulfill the promise of large area devices on inexpensive substrates, such as paper, plastic etc., it is essential to limit the process temperature to lowest possible values. Consequently, organic materials have traditionally been used, although long-term stability and device mobility were always been the issues of concern. Inorganic materials, e.g., oxide semiconductors, on the other hand, show much superior electrical performance once they are processed at high temperatures. However, a reduction in the process temperature drastically reduces the device performance. This problem can be circumvented by suitable changes in the materials, the inner-lying chemistry or even the device architecture. Research focus in the group now, is to find solutions through these routes so as to reduce the process temperature while keeping the device performance at the same level as high temperature processed electronics.
Group members (left to right): Horst Hahn, Gabriel Marques, Jasmin Aghassi, Ben Breitung, Robert Kruk, Tessy Baby, Surya Singaraju, Parvathy Sukkurji
To carry this forward, in the printed electronics group at Institute of Nanotechnology we focus on the fundamental issues concerning solution-processed/ printed oxide electronics.
One key aspect of our research is that we concentrate on electrolyte-gating approach to ensure extremely high gating efficiency even with oxide semiconductors which when solution-processed usually result large interface/ surface roughness, thereby reducing the dielectric efficiency/ polarizability. However, our composite polymer electrolytes can easily follow any surface corrugation offered by the nanostructured oxide semiconductors towards a highly conformal semiconductor/ dielectric interface.
Equipments: INT boasts of a rich variety of equipment used for conducting nano-micro electronics research and to fabricate thin film electronics.
From spin coating to metal evaporators for deposition of thin films, from thermal box furnace to photonic curing instruments for thin film preparation; from X-ray diffractometers to X-ray photoelectron spectroscopy for material characterization; from atomic force microscopy to transmission electron microscopy for imaging and morphological studies; and a multitude of oscilloscopes and Keithley multimeters and Agilent probe station for electrical characterization, there is a huge scope for exciting research both within the printed electronics group and by cooperation with sub-groups at the Institute of Nanotechnology.
MERAGEM: Graduate school for Printable Electronics in cooperation with Karlsruhe Institute of technology and Hochschule, Offenburg. The school is supported by the Ministry of Science, Research and Arts, Baden-Württemberg, Germany. The school has two coordinating professors and cooperation is spread from the Institute of Nanotechnology and Chair of Dependable Nano Computing at KIT and the Department of Electrical Engineering at Offenburg University of Applied Sciences.