Silicon Carbide (SiC) is the material with the wide band-gap (3.26 eV), high critical electric field (∼2.3 MV/cm), and high bulk electron mobility (∼900 cm2/Vs). These electronic properties allow attractive features, such as high breakdown voltage, high-speed switching capability, and high temperature operation compared to Si devices. In general, device design has a significant effect on the switching and electrical characteristics. It is known that in this paper, we demonstrated that the switching performance and breakdown voltage of IGBT is dependent with doping concentration of p-base region and drift layer by using 2-D simulations. As a result, electrical characteristics of SiC-IGBT deivce is higher breakdown voltage (VB= 1,600 V), lower on-resistance (Ron= 0.43 mΩ·cm2) than Si-IGBT. Also,we determined that processing time and cost is reduced by the depth of n-drift region of IGBT was reduced.

The optimal structure of 1-3 piezocomposites has been determined by controlling polymer properties, ceramic volume fraction, thickness of composite and aspect ratio of the composite to maximize the TVR (transmitting voltage response), RVS (receiving voltage sensitivity) and FBW (fractional bandwidth) of underwater acoustic transducers. Influence of the design variables on the transducer performance was analyzed with equivalent circuits and the finite element method. When the piezocomposite is vibrating in a pure thickness mode, inter-pillar resonant modes are likely to occur between lattice-structured piezoceramic pillars and polymer matrix, which significantly deteriorate the performance of the piezocomposite. In this work, a new method to design the structure of the 1∼3 type piezocomposite was proposed to maximize the TVR, RVS and FBW while preventing the occurrence of the inter-pillar modes. Genetic algorithm was used in the optimal design.

In this study, electrocaloric effects of Pb-free (Ba0.85Ca0.15)(Ti0.92Zr0.08)O3 ferroelectric ceramics were investigated and discussed using the characteristics of P-E hysteresis loops at wide temperature range from room temperature to 140℃. The remnant polarization Pr and coercive field Ec were decreased with increasing temperature. The temperature change ΔT by the electrcaloric effect was calculated by Maxwell`s relations, and reached the maximum of ∼0.15 at 120℃ under applied electric field of 30 kV/㎝.

In this study, (Na0.525K0.443Li0.037)(Nb0.883Sb0.08Ta0.037)O3 + 0.10 wt%Bi2O3 + 0.35 wt%B2O3 ceramics were prepared by conventional soild-state sintering process. The specimens were sintered at temperature range from 1,060℃ to 1,100℃. XRD (X-ray diffractron), SEM (scanning electron microscope) were used to analyze the crystal structure and microstructural sproperties of specimens. And also, TO-T, TC were observed by the mesurement of temperature dependence of dielectric constant. Excellect physical properties of the piezoelectric constant d33= 170 pC/N, electromechanical coupling factor kp= 0.312, Tc= 315℃ were obtained, respectively, from the specimen sintered at 1,080℃.

In this study, the capacitance and dielectric loss tangent of the silicone rubber which is combined with filler (30 phr∼50 phr) have been measured on the range of 100 Hz∼100 kHz and 30∼170℃. It was found that when the frequency is 0.1 kHz∼100 kHz and the silicone rubber is combined with 30 phr to 50 phr of filler, the capacitance of silicone rubber has increased by about 28.6 pF to 33 pF in 30 phr of filler, about 20 pF to 46.1 pF in 40 phr of filler and about 36.4 pF to 44 pF in 50 phr of filler. It seems that the volume of dielectric loss has gradually increased due to the temperature rise and the rotating of dipole in electric field through the electric dipole generated by the Si-O group which is induced by adding of filler, or the carbonyl group which is caused by oxidation. It seems that the dielectric dispersion in 0.1 kHz is caused by molecular motion of Siloxane group in main chain, and the dielectric dispersion in 10 kHz is caused by molecular motion of Methyl group in side chain.

We investigated the characteristics of the silicon oxy-nitride and nitride films grown by plasma-enhanced chemical vapor deposition (PECVD) at the low temperature with a varying NH3/N2O mixing ratio and a fixed SiH4 flow rate. The deposition temperature was held at 150℃ which was the temperature compatible with the plastic substrate. The composition and bonding structure of the nitride films were investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Nitrogen richness was confirmed with increasing optical band gap and increasing dielectric constant with the higher NH3 fraction. The leakage current density of the nitride films with a high NH3 fraction decreased from 8X10-9 to 9X10-11(A/cm2 at 1.5 MV/cm). This results showed that the films had improved electrical properties and could be acceptable as a gate insulator for thin film transistors by deposited with variable NH3/N2O mixing ratio.

Effect of multi-stacked layer (MSL), 0.1 mol (M) and 0.3 mol (M) hafnium oxide (HfO2)alignment layers were fabricated via a solution-process for LCs orientation. The solutions were spin-coated and annealed in a furnace. MSL consists of three sub-layers using 0.1 M solution,mono-layer (ML) is composed of 0.3 M HfO2 solution. Then ion-beam irradiation was treated with 1.8keV for 2 min. HfO2-based LC cells were investigated through photographs, pre-tilt angle using crystal rotation method, X-ray photoelectron spectroscopy (XPS) measurement, and surface roughness using atomic force microscopy(AFM) for their characteristic research. Good LC orientation characteristics were observed on MSL HfO2 surface. The LC alignment mechanism on MSL HfO2 and ML HfO2 surfaces was attributed to van der Waals (VDW) interaction between the LC molecular and substrate surface.

In this paper, we carried out the investigations of both etch characteristics and mechanisms for the SnO2 thin films in O2/BCl3/Ar plasma. The dry etching characteristics of the SnO2 thin films was studied by varying the O2/BCl3/Ar gas mixing ratio. We determined the optimized process conditions that were as follows: a RF power of 700 W, a DC-bias voltage of -150 V, and a process pressure of 2 Pa. The maximum etch rate was 509.9 nm/min in O2/BCl3/Ar=(3:4:16 sccm) plasma. From XPS analysis, the etch mechanism of the SnO2 thin films in the O2/BCl3/Ar plasma can be identified as the ion-assisted chemical reaction while the role of ion bombardment includes the destruction of the metal-oxide bonds as well as the cleaning of the etched surface form the reaction products.

In this study, we fabricated a micro Pb(Zr,Ti)O3 (PZT) film piezoelectric cantilever with a Si proof mass and dual beams through MEMS process. The size of the beam and the integrated Si proof mass were about 4,320 μm × 290 μm × 12 μm and 1,380 μm × 880 μm × 450 μm each. To reduce the air damping and have the larger displacement of dual beams was used for design. After mounting micro PZT film piezoelectric cantilever on shaker, we measured the resonance frequency and a output voltage while making resonant frequency changed. The resonant frequency and the highest average power of the cantilever device were 110.2 Hz and 0.36 μW each, at 0.8 g acceleration and 23.7 kΩ load resistance,respectively.

In this study, the surface modification of copper foil using an inductively coupled O2 / Ar plasma as O2 gas fraction (0∼100%) was investigated in order to improve the surface characteristics. After plasma treatment, the measurement of the surface roughness, surface contact angle and surface energy were performed for the surface analysis of copper foil. As a result, the surface roughness and the surface energy were increased. And plasma diagnostics was performed by a double Langmuir probe (DLP) and optical emission spectroscopy (OES). Using these results, the plasma surface modification mechanism was investigated.

We give a textured front on silicon wafer for high-efficiency solar cells by using micro contact printing method which uses PDMS (polydimethylsiloxane) silicon rubber as a stamp and SAM (self assembled monolayer)s as an ink. A random pyramidal texturing have been widely used for a front-surface texturing in low cost manufacturing line although the cell with random pyramids on front surface shows relatively low efficiency than the cell with inverted pyramids patterned by normal optical lithography. In the past two decades,the micro contact printing has been intensively studied in nano technology field for high resolution patterns on silicon wafer. However, this promising printing technique has surprisingly never applied so far to silicon based solar cell industry despite their simplicity of process and attractive aspects in terms of cost competitiveness. We employ a MHA (16-mercaptohexadecanoic acid) as an ink for Au deposited SiO2/Si substrate. The SiO2 pattern which is same as the pattern printed by SAM ink on Au surface and later acts as a hard resist for anisotropic silicon etching was made by HF solution, and then inverted pyramidal pattern is formed after anisotropic wet etching. We compare three textured surface with different morphology (random texture, random pyramids and inverted pyramids) and then different geometry of inverted pyramid arrays in terms of reflectivity.

Recently, energy harvesting technologies are considered as the great alternatives to reduce the dependency on secondary batteries. In this paper, we proposed PCB type energy harvester which can be directly integrated with other electronic components on same board. To form the three dimensional coil structure, two PCBs with patterned metal lines are solder bonded. For magnetic induction, inside of coil structure was filled with magnetic substance and rotary motioned external magnets are applied to near the harvester. The effects of metal wire width on PCB, thickness of magnetic substance, and frequency of rotary motion on energy harvesting performance are analyzed by computer simulation and experiments. Experimental results showed 29.89 ㎼ of power generation performance at the frequency of 5.2 Hz and it is shown that designed harvester can be effectively applied on vibration environment with very limited frequency.