Garlapati, Suresh (2017)
Low Temperature Processing of Printed Oxide Transistors.
Technische Universität Darmstadt
Ph.D. Thesis, Primary publication
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Low Temperature Processing of Printed Oxide Transistors | ||||
Language: | English | ||||
Referees: | Hahn, Prof. Dr. Horst ; von Seggern, Prof. Dr. Heinz | ||||
Date: | 22 February 2017 | ||||
Place of Publication: | Darmstadt | ||||
Date of oral examination: | 19 December 2016 | ||||
Abstract: | Solution processed/printed electronics have gained a lot of attention in recent years because they are inexpensive, easy to fabricate, can be produced on very large areas and on all kinds of substrates. The choice of suitable functional/active materials that can be printed is of essential for the performance of the electronic devices in printed electronics. In case of printed field-effect transistors (FETs), which are elemental building blocks of most logic circuits, the right choice of solution-processable semiconductors is the key to obtain high performance electronic devices. In this regard, inorganic oxide semiconductors are considered as a suitable material, because of their excellent electronic transport properties, i.e., high intrinsic charge carrier mobility, in combination with the high thermal and environmental stability. In the design of FETs, apart from the semiconductors, gate insulators/dielectrics play a crucial role. In the present thesis, printable composite solid polymer electrolyte (CSPE) is chosen as gate insulator due to its high capacitance (1-10 μF/cm2). Furthermore, CSPEs provide extremely conformal interfaces to the rough oxide semiconductor channel layer, which is the key for high gating efficiency and exceptional device performance. Two different approaches, i.e., oxide precursors and nanoparticle dispersions, are used to print the semiconductor channels of FETs. The FETs are prepared from appropriate indium oxide precursors, which are annealed at different temperatures (300-500 °C) to be converted to the oxide; however, the devices need to be heated to 400 °C in order to achieve the best electrical performance characterized by a field effect mobility as high as 126 cm2/Vs and a sub-threshold slope of 68 mV/decade, which is close to the theoretical limit. Furthermore, the effect of the annealing rate on the performance of FETs has been studied. In addition to the single components (FET), complementary metal oxide semiconductor (CMOS) inverters and common source amplifiers have been prepared following a similar fabrication route using indium oxide and copper oxide precursors (annealed at 400 °C). The CMOS inverters have demonstrated a very high signal gain of 21 at 1.5 V. As a second approach and avoiding high processing temperatures, a novel chemical curing method for nanoparticles has been adopted, resulting in a field-effect mobility value of 12.5 cm2/Vs, strikingly high for a nanoparticulate channel completely processed at room temperature (RT). CMOS inverters based on chemically cured indium oxide and copper oxide nanoparticle dispersions have been prepared, which show a signal gain of 18 at 1.5 V. Another novel technique, i.e. photonic curing, has also been used to fabricate printed FETs on plastic substrates at low temperatures. Precursor-based FETs cured by UV-laser and UV-visible light demonstrate mobility values of 15 and 50 cm2/Vs, whereas nanoparticulate-based FETs by the same methods show mobilities of 12 and 8 cm2/Vs, respectively. These values in comparison with those of organic semiconductors verify the outstanding performance of FETs processed at low temperatures (in some cases, even at RT). Furthermore, the low operating voltages (≤ 2V) can be very attractive for battery compatible and portable electronic devices. |
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URN: | urn:nbn:de:tuda-tuprints-59998 | ||||
Classification DDC: | 600 Technology, medicine, applied sciences > 600 Technology 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering |
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Divisions: | 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences > Material Science > Electronic Materials |
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Date Deposited: | 22 Feb 2017 13:16 | ||||
Last Modified: | 01 Dec 2023 08:58 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/5999 | ||||
PPN: | 399879706 | ||||
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