Jai-Kyeong Kim

Quantitative analysis of microstructure and its related electrical property of SOFC anode, Ni–YSZ cermet

Abstract The microstructural and electrical properties of Ni–YSZ composite anode of solid oxide fuel cells (SOFC) were investigated. We measured the electrical conductivity via 4-probe DC technique as a function of Ni content (10–70 vol.%) in order to examine the correlation with the microstructure of Ni–YSZ cermet. Image analysis based on quantitative microscopic theory was performed to quantify the microstructure of Ni–YSZ composite. The size and distribution, contiguity and interfacial area of each phase or between the phases could be obtained from the image analysis. According to image analysis, contiguity between the same phases was simply dependent on the amount of that phase itself while the contiguity between different phases was greatly influenced by the amount of Ni phase because the overall microstructural changes were mainly controlled by the coarsening of Ni phase. These similarly quantified microstructural properties were used for the characterization of the electrical properties of Ni–YSZ cermet.

Multiwall carbon nanotube sensor for monitoring engine oil degradation

An engine oil condition sensor based on multiwall carbon nanotubes was fabricated with the screen printing method. Carbon nanotube (CNT) paste was printed between two parallel-aligned electrodes. The conductivity change in the engine oil according to mileage was measured by using CNT oil sensor. The sensor output was compared with total acid number (TAN) to determine the remaining useful life of the engine oil. It was found that the sensor output was closely similar to TAN of the engine oil. As a result, a real-time engine oil condition monitoring sensor can be realized using CNTs as sensitive materials.

Performance Improvement of Organic Thin-Film Transistors by Electrode/Pentacene Interface Treatment Using a Hydrogen Plasma

Pentacene-based organic thin-film transistors (TFTs) have been fabricated with and without treatment by hydrogen (H2) plasma at the interface between the electrode and the pentacene surface. Processing with a H2 plasma was carried out in a plasma-enhanced chemical vapor deposition with varying treatment times. The interface treatment by H2 plasma resulted in improved device electrical properties. Removal of oxygen from the pentacene surface occurs due to slight etching by the plasma. Sufficient flux density of the H2 plasma leads to full pentacene-surface coverage by rearranging the hydrogen with carbon instead of oxygen. Atomic force microscopy profiles reveal the morphology changes of the pentacene surface after treatment, and secondary ion mass spectrometry shows the change via compositional depth profiles indicating H2 , O2, and C-H binding. Hydrogen treatment, therefore, appears to modify the interface by removing the surface oxygen layer, resulting in better performance of the organic TFT

P-100: Field-Emission Properties of Photosensitive Carbon Nanotube Using Ethanol

To investigate emission properties of the photosensitive carbon nanotube emitters using ethanol as developer, a photosensitive carbon nanotube paste was formulated. for patterning of carbon nanotube paste, backside exposure and development process were carried out after screen printing and drying process. Ethanol is not only formed pattern but also removed organic vehicles in the photosensitive carbon nanotube film. The emission properties of patterned carbon nanotube film with and without firing were evaluated.

39.1: A Novel Organic Thin Film Transistor Fabricated by Low‐Cost Process

Organic thin film transistors are fabricated on the plastic substrates through four-level mask process without patterning for photolithography in order to approach a simple fabrication process. KIST-JM-1 as an organic molecule for self—assembly monolayers is deposited on the surface of the zirconium oxide gate dielectric layer for the better device performance. The effect of gate dielectric surface modification on the field effect mobility of OTFTs has been examined and these prototype organic transistors showed the excellent electrical characteristics such as the field effect mobility > 0.66cm2/Vs and Ion/Ioff > 105.

P-8: Hydrogen Plasma Treatment on the Electrical Characterization of Inverted Staggered Pentacene Thin Film Transistors

In order to reach the high electrical quality of organic thin film transistors OTFTs such as high mobility and on-off current ratio, it is strongly desirable to study the enhancement of electrical properties in OTFTs. Here, we report the novel method of hydrogen plasma treatment to improve electrical properties in inverted staggered OTFTs based on pentacene as active layer. To certify the effect of this method, we compared the electrical properties of normal device as a reference with those of device using the novel method. In result, the normal device as a reference making no use of this method exhibited a field effect mobility of 0.055 2/Vs, on/off current ratio of 103, threshold voltage of −4.5 V, and subthreshold slope of 7.6 V/dec. While the device using the novel method exhibited a field effect mobility of 0.174 2/Vs, on/off current ratio of 106, threshold voltage of −0.5 V, and subthreshold slope of 1.49 V/dec. According to these results, we have found the electrical performances in inverted staggered pentacene TFT owing to this method are remarkably enhanced. So, this method plays a key role in highly improving the electric performance of OTFTs. Moreover, this method is the first time yet reported for any OTFTs.