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Advanced Electronic Materials and Devices through Novel Processing Paradigms

Final Report Summary - AMPRO (Advanced Electronic Materials and Devices through Novel Processing Paradigms)

The AMPRO project seeks to combine unconventional electronic materials with novel fabrication methods to develop low cost devices for application in the broad areas of (i) transistors for large area electronics; (ii) integrated nanoelectronics; and (iii) optical sensors.

The work undertaken during the AMPRO project has led to the development of novel materials systems such as metal oxide semiconductors with enhanced charge transporting characteristics and applied in a high electron mobility metal oxide transistors and integrated circuits, as well as in semi-transparent light-sensing photo-transistors. the development of nanostructured functional transistors fabricated on-demand via scanning thermal nanolithography, has also been demonstrated for the first time using different materials and processing methodologies.

Part of the work focused on advanced metal oxide semiconductors with primary focus on the identification and use of materials with decomposition temperatures that are compatible with temperature sensitive and inexpensive substrate materials such as plastic. In some cases the combination of new material concepts with innovative processing paradigms led to devices with electron transporting characteristics well beyond the state-of-the-art transistor technologies. The superior operating characteristics coupled with the simple and low-temperature manufacturing, has enabled the development of logic circuits comprised of a number of transistors, further demonstrating the potential of the proposed approach.

In the area of plastic nanoelectronics, research activity focused in combining thermally transformable semiconductors with scanning thermal lithography for the development of on-demand patterned nano-electronic devices such as field-effect transistors onto arbitrary substrate materials. We successfully demonstrated the first fully functional transistor based on organic semiconducting nanoribbons patterned by scanning thermal lithography in ambient conditions onto arbitrary shapes and substrate materials. The research also led to significant improvements in the patterning speed further demonstrating the potential of scanning thermal lithography as a viable tool for on-demand manufacturing of nano-structured electronics. In parallel to the work on thermal scanning lithography, we also developed a novel method for forming nanogaps between different metal electrodes on arbitrary substrates. Inter-electrode spacing down to 10s of nanometres has been demonstrated between symmetric as well as asymmetric metals including gold, aluminium, indium tin oxide and titanium. By taking advantage of these unique novel coplanar nanogap electrode architectures, we demonstrated a plethora of functional opto-/electronic devices including, organic photodetectors, radio frequency Schottky diodes, and non-volatile memory cells.

Finally, work on light-sensing transistors focused on optical sensitization of ultra-thin layers of otherwise transparent metal oxides channel material. Light sensitization was successfully demonstrated via functionalisation of suitable light-absorbing dyes onto the surface of the thin oxide transistor channel. The presence of the dye was found to have a dramatic impact on the operating characteristics of the resulting transistors upon illumination with suitable light i.e. wavelengths absorbed by the organic dye. By exploring this unique approach, we demonstrated phototransistors that are highly transparent but extremely photo-responsive due to the signal gain properties of the device architecture employed.