This research was about shielded trench gate power MOSFET for low voltage and high speed. We used T-CAD tool and carried out process and device simulation for exracting design and process parameters. The exracted parameters was used to design shieled and conventional trench gate power MOSFET. And The electrical characteristics of shieled and conventional trench gate power MOSFET were compared and analyzed for their power device applications. As a result of analyzing electrical characteristics, the recorded breakdown voltages of both devices were around 120 V. The electric distributions of shielded and conventional trench gate power MOSFET was different. But due to the low voltage level, the breakdown voltage was almost same. And the other hand, the threshold voltage characteristics of shielded trench gate power MOSFET was superior to convention trench gate power MOSFET. In terms of on resistance characteristics, we obtained optimal oxied thickness of 3 ㎛.

Recently, macroporous ceramic materials with high electrical conductivity and mechanical strength are urgently needed for semiconductor and display manufacturing devices. In this work, we obtained electro-conducting macroporous aluminosilicate ceramics having surface resistivity of 108~1,010 ohm by dispersing electro-conducting carbon in ceramic matrix. By addition of 0.5~3.0 wt% frit glass, chemical bonding between grains was strengthened, and flexural strength was enhanced up to 160 MPa as a result. We evaluated the characteristics of present ceramics as vacuum chuck module for liquid crystal display display manufacturing devices.

This study focuses on the effects of doping Zn₂BiVO₆ and Co₃O₄ on the sintering and electrical properties of ZnO; where, ZZ consists of 0.5 mol% Zn₂BiVO₆ in ZnO, and ZZCo consists of 1/3 mol% Co₃O₄ in ZZ. As ZnO was sintered at about 800℃, the liquid phases, which are composed of Zn₂BiVO₆ and Zn₂BiVO₆-rich phases, were found to be segregated at the grain boundaries of sintered ZZ and ZZCo, respectively, which demonstrates that V_o^·(0.33~0.36 eV) are formed as dominant defects according to the analysis of admittance spectroscopy. As Co₃O₄ is doped to ZZ, the resistivity of ZnO decreases to ~38%, while donor density (N_d), interface state density (N_t), and barrier height (Φ_b) increase twice higher than those of ZZ, according to C-V characteristics. This result harbingers that ZZCo and its derivative compositions will open the gate for ZnO to be applied as more progressive varistors in the future, as well as the advantageous opportunity of manufacturing ZnO chip varistors at lower sintering temperatures below 900℃.

SnO₂/Ag/Nb₂O₅/SiO₂/SnO₂ multilayer films were prepared on glass substrate by sequential using RF/DC magnetron sputtering at room temperature. The influence of top SnO₂ layer thickness on optical and electrical properties of the multilayer films was investigated. Experimentally measured results exhibit transmittances over 84.3 ~ 85.8% at 550 nm wavelength. As the top SnO₂ layer thickness increased from 40 to 55 nm, the sheet resistance (Rs) increased from 5.81 to 6.94 Ω/sq. The Haacke`s figure of merit (FOM) calculated for the samples with various SnO₂ layer thicknesses was a maximum at 45 nm (35.3 × 10^-3 Ω^-1).

This work reports the phase-change behavior and thermal stability of doped GeSbTe/GeSbTe bilayers. We prepared the bilayers using RF sputtering, and annealed them at annealing temperature ranging from 100℃ to 400℃. The sheet resistance of the bilayer decreased and saturated with increasing annealing temperature, and the saturated value was close to that of pure GeSbTe film. The surface of the bilayer roughened at 400℃, which corresponds to the surface roughening of doped GeSbTe film. Mixed phases of face-centered cubic and hexagonal close-packed crystalline structures were identified in the bilayers annealed at elevated temperature. These results indicate that the phase-change behavior of the bilayer depends on the concurrent phase-transitions of the two GeSbTe-based films. The dopants in the doped GeSbTe film were diffused out at annealing temperatures of 300℃ or higher, which implies that the thermal stability of the bilayer should be considered for its application in phase-change electronic devices.

We were designed the hole transport layer of the new composite skeleton structure having a high charge mobility and thermal stability. In this paper, a hole transport layer material based on thiophene molecular structure capable of hole mobility characteristics and high triplet energy was designed and synthesized. The structures and properties of the synthesized compounds were characterized by NMR, fluorescence spectroscopy and energy band gap. As a result of NMR measurement, it was confirmed that when analyzing the integrated type with the position where the measured peak is displayed, it agrees with the structure of hole transport materials. The emission characteristics of the hole transport layer material showed absorption characteristics at 412 nm and 426 nm, respectively, and exhibited emission characteristics in the range of 469 nm and 516 nm.

In this paper, the flux-lock type superconducting fault current limiter (SFCL) using double quench was suggested and its transient current limiting characteristics were analyzed. The suggested flux-lock type SFCL using double quench consists of two magnetically coupled windings and two high-T_C superconducting (HTSC) elements connected in series with each winding. To analyze the transient current limiting characteristics of the flux-lock type SFCL using double quench, the short-circuit tests according to the fault angles, which affect the transient component of the fault current right after the fault occurs, were executed. From the comparative analysis for the short-circuit tests at both 0° and 90° fault angles, the useful transient current limiting operations of the suggested flux-lock type SFCL through the double or the single quench occurrence were confirmed.

In this paper, the magnetization characteristics and the stored energy of magnetically coupled superconducting fault current limiter (SFCL)s using single and double high-Tc superconducting (HTSC) elements were compared. To analyze the magnetization characteristics and the stored energy, the magnetizing current and the flux linkage, which were derived from the electrical equivalent circuit of the SFCL using single and double HTSC elements, were calculated from the voltages and the current measured in the short-circuit tests. Through the comparative analysis on the magnetization characteristics and the stored energy for SFCL using sing and double HTSC elements, the magnetically coupled SFCL using double HTSC elements was shown to be more effective than the SFCL using single HTSC element from the point of view of the magnetic saturation.

This paper compared current limiting characteristics of superconducting fault current limiter (SFCL) using E-I core due to the location of windings. Since E-I core has three legs and two magnetic paths, the current limiting characteristics of SFCL were expected to be affected by the installation location of windings, either center leg or right/left leg. To analyze its characteristics, the electrical equivalent circuit of the SFCL were derived and the electromagnetic analysis for the SFCL with the designed structure were performed. From the short-circuit tests, the hysteresis curve and the voltage-current trajectory of the SFCL due to the installation location of windings were extracted and compared each other. The SFCL with windings in the center leg of E-I core was shown to be larger magnetizing inductance compared to the one with windings in the right or left leg of E-I, which was analyzed from the hysteresis curve. In addition, larger decreased fault current right after the fault occurrence in the SFCL with windings in the center leg of E-I core was confirmed than the SFCL with windings in the right or left leg of E-I.

In this research, the development of fabrication technique of bulk YBaCuO superconductors for application was studied. In fluence of BaZrO₃ addition on magnetization characteristics of thermal pyrolysis textured YBaCuO superconductor was investigated. Fine BaZrO₃ particle were dispersed within the textured YBaCuO matrix by means of the thermal pyrolysis processing. Magnetic levitation force for YBaCuO superconductors were obtained using Nd-B-Fe permanent magnet, at 77 K and at the magnetic field from 0 to 5.3 K gauss. In the unadded superconductor and 5 wt% BaZrO₃ addition, anomalous magnetization behavior, which is characterized by the intermediate magnetic field, was observed at 77 K. Critical current density was about few hundreds A/㎠ and the magnetic characteristics increased slightly by addition of BaZrO₃ powder. Maximum magnetic force was obtained in the YBaCuO superconducting bulk with 3 wt.% BaZrO₃ addition.

Highly photosensitive and wide bandgap amorphous silicon oxide (a-SiO_x:H) films were developed at low temperature ranges (100~150℃) with employing plasma-enhanced chemical vapor deposition by optimizing H₂/SiH₄ gas ratio and CO₂ flow. Photosensitivity more than 10⁵ and wide bandgap (1.81~1.85 eV) properties were used for making the a-SiO_x:H thin film solar cells, which exhibited a high open circuit voltage of 0.987 V at the substrate temperature of 100℃. In addition, a power conversion efficiency of 6.87% for the cell could be improved up to 7.77% by employing a new n-type nc-SiO_x:H/ZnO:Al/Ag triple back-reflector that offers better short circuit currents in the thin film photovoltaic devices.

We have studied the effects of Ag on the characteristics of Sn₄₃Bi₅₇Ag_x(wt%) lead-free solders for photovoltaic ribbon. Ag atoms in the solder formed an alloy phase of Ag₃Sn after reacting with some part of Sn atoms, while they did not react with Bi atoms, but decreased the mean size of Bi solid phase and the thickness of solder. When Ag atoms of 3.0 wt% was added to eutectic Sn₄₃Bi₅₇(wt%) solder, it showed the optimally useful results that the peel strength of photovoltaic ribbon greatly increased and the sheet resistance of the solder decreased. In the meanwhile, the eutectic Sn₄₃Bi₅₇(wt%) solder showed a low melting temperature of 138.9℃, and showed a very similar result regardless of the added amount of Ag atoms.

The power conversion efficiency of organic polymer solar cells was enhanced by introducing a ferroelectric polymer layer at the interface between active layer and metal electrode. The power conversion efficiency was increased by 50% through the enhancement of the open circuit voltage. To investigate the role of the ferroelectric layer on the dissociation process of the excitons, non-radiative portion of the exciton decay was directly measured by using photoacoustic technique. The results show that the ferroelectric nature of the buffer layer does not play any roles on the dissociation process of the excitons, which indicates the efficiency enhancement is not due to the ferroelectricity of the buffer layer.