The vigorous response of multiwalled carbon nanotubes (MWNTs) to microwave irradiation, leading to the release of a large amount of heat, is used to locally melt a plastic matrix adjacent to the nanotubes within a period of seconds. This results in the intercalation of the MWNTs into the polymer matrix at room temperature without any physical damage to the polymer. The so‐called “microwave welding” approach creates a new paradigm for the formation of very strong MWNT–polymer bonds without the use of any adhesive, and represents a significant step forward for the fabrication of functional nanotube composites. Here, we demonstrate the implications of the anisotropic alignment of MWNTs in polymers, patterned conductors/resistors for soft electronics, and high‐strength composites, where the MWNTs are ‘soldered' to flexible polymer substrates.
An nitrogen-implanted p-type ZnO film has been grown on a Si substrate buffered with Si3N4 using radio-frequency magnetron sputtering. The Si3N4 buffer layer can effectively improve film stoichiometry and reduce the formation of oxygen vacancies compared to ZnO on Si. The electrical properties of the p-type ZnO films implanted with 5×1012–1×1014 cm−2 N+ dose show a hole concentration of 5.0×1016–7.3×1017 cm−3, hole mobility of 2.51–6.02 cm2/V s, and resistivity of 10.11–15.3 Ω cm. The p-type ZnO films also showed an excellent crystallinity and a strong ultraviolet emission peak near 3.30 eV at room temperature. Moreover, as evidenced by extended x-ray absorption fine structure analysis, the local structure of the p-type ZnO films was changed due to the substitution of nitrogen ions for oxygen ions in p-type ZnO films. Our finding of p-type ZnO films grown on a Si3N4/Si substrate could provide a simple method to fabricate reproducible p-type ZnO films on silicon substrate for the development of large-scale optoelectronic integration device.
Lead zirconate titanate (Pb(1.1)(Zr(0.52)Ti(0.48))O(3)) thin films of thickness 260 nm on Pt/Ti/SiO(2)/Si substrates were densified by 2.45 GHz microwave annealing. The PZT thin films were annealed at various annealing temperatures from 400 to 700 °C for 30 min. X-ray diffraction showed that the pyrochlore phase was transformed to the perovskite phase at 450 °C and the film was fully crystallized. The secondary (again pyrochlore) phase was observed in the PZT thin films, which were annealed above 550 °C. The surface morphologies were changed above 550 °C of the PZT thin films due to the secondary phase. Higher dielectric constant (ε(r)) and lower dielectric loss coercive field (E(c)) were achieved for the 450 °C film than for the other annealed films.
The drastic temperature rise of multiwall carbon nanotubes (MWCNTs) in response to microwave irradiation was applied to weld a MWCNT paste on a polymer substrate within a few seconds. It provides a strong bonding between the MWCNT and polymer without thermal damage to the substrate. A flexible field emitter was made from MWCNT microwave welded on polycarbonate, showing excellent electrical conduction and field-emission properties even under bending. The field emitter works with a turn-on voltage of 0.8V∕μm due to the direct electron transfer. By this method, printed circuits and field-emission devices can be processed simultaneously within seconds leading to important applications in flexible electronic devices.
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