This paper introduces a biocompatible packaging system for implantable medical device having a hermetic sealing, such that a perfect physical and chemical isolation between electronic medical system and human body (including tissue, body fluids, etc.) is obtained. The hermetic packaging includes an electronic MEMS pressure sensor, power charging system, and bluetooth communication system to wirelessly measure variation of capacitance. The packaging was acquired by Quartz direct bonding and CO₂ laser welding, with a size of width 6 cm × length 10 cm × height 3 cm. Hermetic sealing of the packaged system was tested by changing the pressure in a hermetic chamber using a precision pressure controller, from atmospheric to 900 mmHg. We found that the packaged system retained the same count or capacitance values with sensor 1 - 25,500, sensor 2 - 26,000, and sensor 3 - 20,800, at atmospheric as well as 900 mmHg pressure for 5 hours. This result shows that the packaging method has perfect hermetic sealing in any environment of the human body pressure.

We investigated solution-processed indium-yttrium-oxide (IYO) TFTs using apoly (methyl methacrylate) (PMMA) passivation layer. The IYO semiconductor solution was prepared with 0.1 M indium nitrate hydrate and 0.1 M yttrium acetate dehydrate as precursor solutions. The solution-processed IYO TFTs showed good performance: field-effect mobility of 13.13 ㎠/Vs, a threshold voltage of 8.2 V, a subthreshold slope of 0.93 V/dec, and a current on-to-off ratio of 7.2 × 10⁶. Moreover, the PMMA passivation layers used to protectthe IYO active layer of the TFTs, did so without deteriorating their performance under ambient conditions; their operational stability and electrical properties also improved by decreasing leakage current.

A high-performing photoelectric device was realized for the MoS₂-embedded Si device. MoS₂-coating was performed by an available large-scale sputtering method. The MoS₂-layer coating on the p-Si spontaneously provides the rectifying current flow with a significant rectifying ratio of 617. Moreover, the highly optical transmittance of the MoS₂-layer provides over 80% transmittance for broad wavelengths. The MoS₂-embedded Si photodetector shows the sensitive photo-response for middle and long-wavelength photons due to the functional MoS₂-layer, which resolves the conventional limit of Si for long wavelength detection. The functional design of MoS₂-layer would provide a promising route for enhanced photoelectric devices, including photovoltaic cells and photodetectors.

The designing approaches with consideration offabrication process technologies for high-frequency, high-powered, silicon-based static induction thyristors (SITH) are presented. The effects of doping concentration and thickness on the I-V characteristics and power performance of the devices are discussed. The dependence of SITH switching performances on material, geometric structure, and technological parameters isexamined by using two-dimensional simulations. Thickepitaxy technology is found to be one of the most critical steps in realizing the proposed structure and switching times, t_off, of SITH, which may be reduced to below ~0.26 μs for the proposed 1,700 V SITH devicesafter optimization.

In this paper, we discuss β-Ga₂O₃ thin films that have been grown on freestanding GaN (FS-GaN) using furnace oxidation. A GaN template was grown by horizontalhydride vapor phase epitaxy (HVPE), and FS-GaN was fabricated using the laser lift off (LLO) system. To obtain β-Ga₂O₃ thin film, FS-GaN was oxidized at 900~1,100℃. Surface and cross-section of prepared β-Ga₂O₃ thin films were observed by field emission scanning electron microscopy (FE-SEM). The single crystal FS-GaNs were changed to poly-crystal β-Ga₂O₃. The oxidized β-Ga₂O₃ thin film at 1,100℃ was peel off from FS-GaN. Next, oxidation of FS-GaNwas investigated for 0.5~12 hours with variation of the oxidation time. The thicknesses of β-Ga₂O₃ thin films were measured from 100 nm to 1,200 nm. Moreover, the 2-theta XRD result indicated that (-201), (-402), and (-603) peaks were confirmed. The intensity of peaks was increased with increased oxidation time. The β-Ga₂O₃ thin film was generated to oxidize FS-GaN.

IZO transistors with Al₂O₃ as gate dielectrics have been investigated. To improve permittivity in an ambient dielectric layer, we grew Al₂O₃ by atomic layer deposition directly onto the substrates. Then, we prepared IZO semiconductor solutions with 0.1 M indium nitrate hydrate [In(NO₃)₃·xH₂O] and 0.1 M zinc acetate dehydrate [Zn(CH₃COO)₂·2H₂O] as precursor solutions; the IZO solution made with a molar ratio of 7:3 was then prepared. It has been found that these oxide transistors exhibit low operating voltage, good turn-on voltage, and an average field-effect mobility of 0.90 ㎠/Vs in ambient conditions. Studies of low-voltage driving of IZO transistors with atomic layer-deposited high-k Al₂O₃ as gate dielectric provide data of relevance for the potential use of these materials and this technology in transparent display devices and displays.

We report on amorphous thin-film transistors (TFTs) with indium zinc oxide (IZO) channel layers that were fabricated via a solution process. We prepared the IZO semiconductor solution with 0.1 M indium nitrate hydrate and 0.1 M zinc acetate dehydrate as precursor solutions. The solution- processed IZO TFTs showed good performance: a field-effect mobility of 7.29 ㎠/Vs, a threshold voltage of 4.66 V, a subthreshold slope of 0.48 V/dec, and a current on-to-off ratio of 1.62×10⁵. To investigate the static response of our solution-processed IZO TFTs, simple resistor load-type inverters were fabricated by connecting a 2-MΩ resistor. Our IZOTFTbased N-MOS inverter performed well at operating voltage, and therefore, isa good candidate for advanced logic circuits and display backplane.

Aluminum nitride fibers were synthesized by carbothermal reduction and nitridation of precursor fibers obtained by electrospinning. The starting materials used to synthesize the AlN fibers were Al(NO₃)₃·9H₂O and urea. Polyvinylpyrrolidone with increasing viscidity was used as the carbon source to obtain a composite solution. The mixed solution was drawn into a plastic syringe with a stainless steel needle, which was used as the spinneret and connected to a 20 kV power supply. A high voltage was supplied to the solution to facilitate the formation of a dense net of fibers on the collector. The precursor fibers were dried at 100℃ and then heated to 1,400℃ for 1 h in a microwave furnace under N2 gas flow for the carbothermal reduction and nitridation. X-ray diffraction studies indicated that the synthesized fibers consisted of the AlN phase. Field emission scanning electron microscopy studies indicated that the diameter of the calcined fibers was approximately 100 nm.

In this study, Li₂MnSiO₄ cathode material and LiPON solid electrolyte were manufactured into thin films, and the possibility of their use in thin-film batteries was researched. When the RTP treatment was performed after Li₂MnSiO₄ cathode thin-film deposition on the SUS substrate by a sputtering method, a β-Li₂MnSiO₄ cathode thin film was successfully manufactured. The LiPON solid electrolyte was prepared by a reactive sputtering method using a Li₃PO₄ target and N₂ gas, and a homogeneous and flat thin film was deposited on a Li₂MnSiO₄ cathode thin film. In order to evaluate the electrochemical properties of the Li₂MnSiO₄ cathode thin films, coin cells using only a liquid electrolyte were prepared and the charge/discharge test was conducted. As a result, the amorphous thin film of RTP treated at 600℃ showed the highest initial discharge capacity of about 60 μAh/㎠. In cases of coin cells using liquid/solid double electrolyte, the discharge capacities of the Li₂MnSiO₄ cathode thin films were comparable to those without solid LiPON electrolyte. It was revealed that Li₂MnSiO₄ cathode thin films with LiPON solid electrolyte were applicable in thin film batteries.

Bi₂Te₃-based alloys have been intensively investigated as active materials for thermoelectric power generation devices from low-temperature (< 250℃) waste heat. In the present study, we fabricated Pb-doped, p-type Bi_0.48Sb_1.52Te₃ polycrystalline bulks by using meltsolidification and spark plasma sintering techniques, and evaluated their thermoelectric transport properties in an effort to develop optimized composition for low-temperature power generation applications. The electronic and thermal transport properties of Bi_0.48Sb_1.52Te₃ could be manipulated by Pb doping. As a result, the temperature for a peak thermoelectric performance (zT) gradually shifted toward higher temperatures with Pb content, suggesting that thermoelectric power generation efficiency can be enhanced by controlled Pb doping.

In this study, we design, model, and analyze a compound generator that combines the axial flux permanent magnet (AFPM,) and radial flux permanent magnet (RFPM), which is expected to increase power generation by allowing the magnets to be placed on the upper, lower, left, and right sides of the same-sized generator. Through the design, modelling, and analysis of AFPM and RFPM compound generators, the generator load evaluation results rated output of 500.25 W and efficiency of 87.60%, respectively, at a rated speed of 600 rpm. By employing this complex generation system,these findings are expected to contribute to the activation of a small power generation system.

Eight types of LED packages were manufactured according to the type and composition ratio of phosphors by using commercially available white LED phosphors. CRI (Ra), a conventional color quality evaluation method was evaluated by using manufactured white LED; the Rf, Rg, color vector graphic, and color distortion graphic were evaluated with a new method, IES TM-30-15. The results of the evaluation confirmed that the new method compensated for the disadvantages of CRI, which was found to be inadequate when the color was saturated. The added evaluation index identified the chroma variation and color change. Furthermore, the study showed that the changes of Rf and Rg are small when controlling phosphors based on CRI, questioningthe necessity of identifyingchroma variation and color change.