In the last few years, rapid progress in flexible electronics has been demonstrated by the emergence of exciting products such as flexible displays and e-papers, which are light weight, compact, but also have the potential to incorporate multiple functions. To date, components such as solar cells, memories, sensors, and transistors on flexible substrates have been made of amorphous silicon or organic materials that have low carrier mobility and suffer from reliability issues. In order to integrate multiple circuit functions onto flexible electronics, high performance and ubiquitous logic devices using both n- and p-type materials, that have high mobility, are urgently needed. ZnO is a promising material for such a purpose as it is transparent in the visible spectral range, thus more stable under exposure to visible light. Although the growth of high quality ZnO films has been a challenge, ZnO nanowires (NWs) have demonstrated unique potential as they are typically single crystals and have been shown to exhibit high mobilities over 1000cm2/V.s. However, a great challenge has been p-type doping of the NWs, as background n-type defects (donor) overwhelm the p-type doping (acceptor) effect, thereby limiting the large scale integration of these NWs for device applications. In this GOALI proposal, we articulate our novel strategies to face the aforementioned challenges. Specifically, we aim to: 1) Synthesize single crystals of n-type and p-type ZnO NWs during high temperature deposition, 2) Perform systematic analysis of the defects in ZnO NWs, and understand the dopant (n and p types) compensation mechanisms using a whole host of advanced characterization techniques including high resolution electron microscopy, nanochemical analysis, paramagnetic resonance, and Raman, electron energy loss and photoelectron spectroscopies, 3) Characterize and simulate transport properties of single ZnO NW, randomly orientated NW array and parallel aligned NW arrays through field effect transistor structure to achieve high performance, including high mobility and large on/off ratio, and 4) Explore mass integration of parallel-aligned ZnO NW arrays, as active field effect transistor channels, onto transparent glass and plastic substrates at low temperature. The intellectual merit of this proposal lies in the transformative concepts and approaches that will greatly increase the performance, especially device speed, of transparent electronics. Through a collaborative effort between electrical engineers and materials scientists at Arizona State University and partnering company, Structured Materials Industries, Inc., we will integrate robust and reliable ZnO NW devices onto polymer substrates, beginning with designed synthesis process to understanding their solid state chemistry, and then scaling up for subsequent device integration; following critical pathways have been the bottle neck for further advancements in this field. Furthermore, novel large scale integration strategies will enable bring tangible innovation from concept-to-commercialization at an accelerated pace in this rapidly growing field of flexible electronics. The broader impact of the proposed activity is the integration of high mobility materials, in the form of monolithic NWs, onto transparent substrates. The systematic interdisciplinary approach via synthesis, analytical characterization, scale up, new integration scheme, and performance analysis will lead to hybrid and high performance electronics on transparent and flexible substrates. The educational aspect will also have far reaching consequences. The program will train personnel (including student from a rich pool of underrepresented minorities in Arizona) in a technologically important area, so that they can apply their science and engineering skills in the US industries and research laboratories upon completion. Indeed, collaboration with our industrial partner will provide the pe
|Effective start/end date||9/15/09 → 8/31/13|
- National Science Foundation (NSF): $366,000.00
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