Vertical Transparent Conductive Oxide Transistors on Flexible Substrates
Final Report Abstract
It was the overall goal of the project to fabricate and investigate oxide-semiconductor-based vertical transistors on flexible substrates as a suitable technology for future high-frequency printed circuits. We have adapted the permeable base transistor (PBT) concept, which has led to excellent results for organic semiconductor materials. We were able to fabricate the most important component of the PBT, the Schottky diode, using oxide-based printed semiconductors. Unfortunately, the stability of these layers was so poor that we could not build functional PBTs. However, based on a newly established collaboration, this problem has been solved, and we will continue with the fabrication of full PBTs. Due to these unexpected problems , we decided to continue our work with organic permeable base transistors (OPBTs). Fortunately, due to recent process improvements, we were able to demonstrate a very high yield of device fabrication and excellent device quality, matching or even exceeding the expectations we had for the oxide devices. We established a collaboration supporting our work by developing a physics-based model for these devices. Based on this model, we developed a deep understanding of the underlying transport phenomena. In particular, we found out that neither the size nor the density of the nm-size pinholes in the base is essential for the device performance within the experimental range of parameters. Hence, the OPBTs turned out to be very robust against variations in the process conditions. Finally, using the know-how from the model development, we designed, fabricated, and measured complementary circuits (ring oscillators and inverters). These devices have an excellent yield, show high inverter gain (>30), and the signal delay per stage is as low as 11ns at a supply voltage of only 4V. Hence, with these developments, printed vertical transistors have made major steps ahead and are about to cross the GHz threshold.
Publications
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Integrated complementary inverters and ring oscillators based on vertical-channel dual-base organic thin-film transistors. Nature Electronics, 4(8), 588-594.
Guo, Erjuan; Xing, Shen; Dollinger, Felix; Hübner, René; Wang, Shu-Jen; Wu, Zhongbin; Leo, Karl & Kleemann, Hans
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Organic Permeable Base Transistors – Insights and Perspectives. Advanced Optical Materials, 9(14).
Guo, Erjuan; Dollinger, Felix; Amaya, Baltasar; Fischer, Axel & Kleemann, Hans
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“Novel Concepts for Organic Transistors: Physics, Device Design, and Applications,” Habilitation, TU Dresden (2021).
Hans Kleemann
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“Organic Permeable Base Transistors: Physics and Applications”, Dissertation TU Dresden (2021).
Erjuan Guo
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45‐2: Invited Paper: Towards High‐Performance Organic Transistors for Display and other Applications. SID Symposium Digest of Technical Papers, 53(1), 565-568.
Guo, Erjuan; Wu, Zhongbin; Liu, Yuan; Kleemann, Hans & Leo, Karl
