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121. Highly Transparent Au-Coated Ag Nanowire Transparent Electrode With Reduction In Haze

Author

Kim, Taegeon, Canlier, Ali, Cho, Changsoon, Rozyyev, Vepa, Lee, Jung-Yong, and Han, Seung Min

Abstract

Ag nanowire transparent electrode has excellent transmittance and sheet resistance, yet its optical haze still needs to be improved in order for it to be suitable for display applications. Ag nanowires are known to have high haze because of the geometry of the nanowire and the high light scattering characteristic of the Ag. In this study, a Au-coated Ag nanowire structure was proposed to reduce the haze, where a thin layer of Au was coated on the surface of the Ag nanowires using a mild [Au(en)(2)]Cl-3 galvanic displacement reaction. The mild galvanic exchange allowed for a thin layer of Au coating on the Ag nanowires with minimal truncation of the nanowire, where the average length and the diameter were 13.0 mu m and 60 nm, respectively. The Au-coated Ag nanowires were suspended in methanol and then electrostatically sprayed on a flexible polycarbonate substrate that revealed a clear reduction in haze with a 2-4% increase in total transmittance, sheet resistance ranges of 80-90%, and 8.8-36.8 Ohm/sq. Finite difference time domain simulations were conducted for Au-coated Ag nanowires that indicated a significant reduction in the average scattering from 1 to 0.69 fo Au layer thicknesses of 0-10 nm.

Published
2014

129. Some Insights into Atomic Layer Deposition of MoNxUsing Mo(CO)6and NH3and Its Diffusion Barrier Application

Author

Kim, Tae Hyun, Nandi, Dip K., Ramesh, Rahul, Han, Seung-Min, Shong, Bonggeun, and Kim, Soo-Hyun

Abstract

Deposition providing precise control of the film thickness, low deposition temperature, and noncorrosive byproducts is essential for the efficient fabrication of barrier layers in semiconductor devices. Here, molybdenum nitride (MoNx) is deposited for Cu diffusion barrier application at a relatively low temperature (180–300 °C) by atomic layer deposition (ALD) using molybdenum hexacarbonyl [Mo(CO)6] and ammonia gas (NH3). The density functional theory calculations indicate favorable thermodynamics during the chemisorption of Mo(CO)6on −NH2-terminated Si clusters at 200 °C, confirming the suitability of Mo(CO)6for ALD. However, the films deposited beyond the ALD temperature window are of similar importance though decomposition-induced growth of the film is evident; nevertheless, other advantages exist (e.g., higher growth rate and improved film characteristics). Furthermore, a few experiments using NH3plasma as a reactant show further scope for this process. The as-grown MoNxfilm using thermal ALD is mostly amorphous with significant O impurity. Poorly structured nanocrystalline h-MoN and cubic Mo2N phase are formed in the film above 225 °C. These phases are converted into the crystalline cubic Mo2N phase upon annealing at higher temperature (500–700 °C) in a hydrogen atmosphere. The resistivity of the MoNxfilms decreases sharply with deposition temperature and is significantly reduced further upon post-annealing. The properties of the as-deposited and annealed films are characterized in detail by secondary-ion mass spectroscopy and X-ray photoelectron spectroscopy. The barrier properties against Cu diffusion for the as-deposited thin films (less than 10 nm) grown at 225 and 275 °C are analyzed using ex situ X-ray diffraction (XRD) and electrical impedance spectroscopy (EIS). EIS helps to determine the failure of the MoNxbarrier layer qualitatively by comparing different EIS spectra obtained after annealing at different temperatures. Both XRD and EIS analyses show that the ALD-MoNxfilm deposited at the higher ALD temperature makes a better Cu diffusion barrier layer. This could be attributed to the higher density of the ALD MoNxfilm grown at 275 °C compared with that deposited at 225 °C.

Published
2019
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140. Self-activated ultrahigh chemosensitivity of oxide thin film nanostructures for transparent sensors

Author

Massachusetts Institute of Technology. Department of Materials Science and Engineering, Tuller, Harry L., Moon, Hi Gyu, Shim, Young-Soek, Kim, Do Hong, Jeong, Hu Young, Jeong, Myoungho, Jung, Joo Young, Han, Seung Min, Kim, Jong Kyu, Kim, Jin-Sang, Park, Hyung-Ho, Lee, Jong-Heun, Yoon, Seok-Jin, Jang, Ho Won, Massachusetts Institute of Technology. Department of Materials Science and Engineering, Tuller, Harry L., Moon, Hi Gyu, Shim, Young-Soek, Kim, Do Hong, Jeong, Hu Young, Jeong, Myoungho, Jung, Joo Young, Han, Seung Min, Kim, Jong Kyu, Kim, Jin-Sang, Park, Hyung-Ho, Lee, Jong-Heun, Yoon, Seok-Jin, and Jang, Ho Won

Abstract

One of the top design priorities for semiconductor chemical sensors is developing simple, low-cost, sensitive and reliable sensors to be built in handheld devices. However, the need to implement heating elements in sensor devices, and the resulting high power consumption, remains a major obstacle for the realization of miniaturized and integrated chemoresistive thin film sensors based on metal oxides. Here we demonstrate structurally simple but extremely efficient all oxide chemoresistive sensors with ~90% transmittance at visible wavelengths. Highly effective self-activation in anisotropically self-assembled nanocolumnar tungsten oxide thin films on glass substrate with indium-tin oxide electrodes enables ultrahigh response to nitrogen dioxide and volatile organic compounds with detection limits down to parts per trillion levels and power consumption less than 0.2 microwatts. Beyond the sensing performance, high transparency at visible wavelengths creates opportunities for their use in transparent electronic circuitry and optoelectronic devices with avenues for further functional convergence., Korea (South). Ministry of Intelligence and Economy (Contract K0004114), Korea Institute of Science and Technology (Grant 2E22121), Korea (South). Ministry of Environment (Research Program)

Published
2014

146. Diffusion Kinetics of Oxygen in beta-Titanium Measured by Molten Flux Method

Author

Song, Min Ho, Han, Seung Min, Choi, Good Sun, Min, Dong Joon, Park, Joo Hyun, Song, Min Ho, Han, Seung Min, Choi, Good Sun, Min, Dong Joon, and Park, Joo Hyun

Abstract

The unidirectional diffusion model of oxygen in beta-titanium was investigated based on the molten flux method and was analyzed by combining thermodynamics and kinetics. The interfacial concentration of oxygen could uniformly be maintained by using the Ca(CaO)-CaCl2 flux. The diffusion coefficient of oxygen in beta-Ti has been measured at temperatures from 1273 to 1573 K. The diffusion coefficient of oxygen in beta-Ti was evaluated as a function of temperature, especially at the low oxygen content region (0.025 mass pct O)., QC 20110418

Published
2009
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