Triboelectric nanogenerators (TENGs) are used as self-power sources for various types of devices by converting external waves, wind, or other mechanical energies into electric power. However, obtaining a high-output performance is still of major concern for many applications. In this study, to enhance the output performance of polydimethylsiloxane (PDMS)-based TENGs, highly dielectric TiO2−x nanoparticles (NPs) were embedded as a function of weight ratio. TiO2−x NPs embedded in PDMS at 5% showed the highest output voltage and current. The improved output performance at 5% is strongly related to the change of oxygen vacancies on the PDMS surface, as well as the increased dielectric constant. Specifically, oxygen vacancies in the oxide nanoparticles are electrically positive charges, which is an important factor that can contribute to the exchange and trapping of electrons when driving a TENG. However, in TiO2−x NPs containing over 5%, the output performance was significantly degraded because of the increased leakage characteristics of the PDMS layer due to TiO2−x NPs aggregation, which formed an electron path.
In-Ga-Zn-O (IGZO) films deposited by sputtering process generally require thermal annealing above 300°C to achieve satisfactory semiconductor properties. In this work, microwave and e-beam radiation are adopted at room temperature as alternative activation methods. Thin film transistors (TFTs) based on IGZO semiconductors that have been subjected to microwave and e-beam processes exhibit electrical properties similar to those of thermally annealed devices. However spectroscopic ellipsometry analyses indicate that e-beam radiation may have caused structural damage in IGZO, thus compromising the device stability under bias stress.
The reactions of Cu/Ti/SiO 2 structures at temperatures ranging from 200 to 700 • C have been studied for various Ti thicknesses. X-ray and Rutherford backscattering spectroscopy (RBS) analyses were used to identify the reaction products resulting from Ti reactions in Cu/Ti/SiO 2 systems and the oxygen composition in the unreacted Ti, and revealed a correlation between the oxygen concentration in Ti films and the sequences of the Ti reactions. The reaction products initially formed, at around 300 • C, were a series of Cu-Ti intermetallics (Cu 3 Ti/CuTi) at the Cu-Ti interface with the oxygen dissolved in the Ti moving from the compounds into the remaining unreacted Ti. At 500 • C, the Cu 3 Ti was converted into Cu-rich intermetallics, Cu 4 Ti, which grew at the expense of the CuTi due to the increased oxygen content in the Ti. In addition, the outdiffusion of Ti, to the Cu surface, and the Ti-SiO 2 reactions caused an abrupt increase in the oxygen content in the Ti layer, which placed thermodynamic restraints on further Ti reactions. Furthermore, thinner Ti layers showed a higher increased rate of oxygen accumulation for the same consumption of Ti, which led to significantly reduced Ti consumption. The diffusion barrier properties of SiO 2 for Cu metallization decreased with an increasing Ti thickness.
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