Poly Si TFTs (poly silicon thin film transistors) with p channel those are annealed HT (high t emperature) with gate poly crystalline silicon and LT (low temperature) with metal gate electrode were fabricated on quartz substrate using the analyzed data and compared according to the activated grade silicon thin films and the size of device channel. The electrical characteristics of HT poly-Si TFTs increased those are the on current, electron mobility and decrease threshold voltage by the quality of particles of active thin films annealed at high temperature. But the on/off current ratio reduced by increase of the off current depend on the hot carrier applied to high gate voltage. Even though the size of the particles annealed at low temperature are bigger than HT poly-Si TFTs due to defect in the activated grade poly crystal silicon and the grain boundary, the characteristics of LT poly-Si TFTs were investigated deterioration phenomena those are decrease the electric off current, electron mobility and increase threshold voltage. The results of transconductance show that slope depend on the quality of particles and the amplitude depend on the size of the active silicon particles.

We have analyzed electrical characteristics of spot light solar cell modules and have completed fabrication of spot light solar cell modules. Before we test modules, we have carried about UV test of hologram. As a result of test, we have obtained 165% efficiency of hologram film. the other hand, we obtained 75% efficiency of general films. After we have fabricated solar modules and carried about field test, spot light solar cell modules with hologram have been investigated 17.3 A of Isc and 155.4 W of power.

In this study, the etching characteristics of Al2O3 thin films were investigated using an ICP (inductively coupled plasma) of BCl3/Ar gas mixture. The etch rate of Al2O3 thin films as well as the SiO2/Al2O3 etch selectivity were measured as functions of BCl3/Ar mixing ratio (0∼100% Ar) at a constant gas pressure (10 mTorr), total gas flow rate (40 sccm), input power (800 W) and bias power (100 W). The behavior of the Al2O3 etch rate was shown to be quite typical for ion-assisted etch processes with a dominant chemical etch pathway. To analyze the etching mechanism using DLP (double langmuir probe), OES (optical emission spectroscopy) and surface analysis using XPS (x-ray photoelectron spectroscopy) were carried out.

Effect of pump combinations on the vacuum characteristics of vacuum system was simulate d for optimum design of system. In this investigation, the feasibility of modelling mechanism for VacSim(Multi) simulator was proposed. Simulation results of various pumping combinations showed the possibilities and reliabilities of simulation for the performance of vacuum system in specific semiconductor processing. Simulation of roughing pump presented the expected pumping behaviors based on commercial specifications of employed pumps. Application of booster pump exhibited the high pumping efficiency for middle vacuum range. Combinations of optimum backing pump for diffusion and turbo vacuum system were obtained. And, the predictable characteristics of process application of both simulated systems were also acquired.

Soution-processed ZrInZnO (ZIZO) thin-film transistors (TFTs) with varying Zr content were fabricated. The ZIZO TFT (Zr=20 at. %/Zn) has an optimal performance with the saturation field effect mobility of 0.77 cm2/Vs, the threshold voltage (Vth) of 2.1 V, the on/off ratio of 4.95×10(6), and subthreshold swing (S.S) of 0.73 V/decade. Using this optimized ZIZO TFT, the positive and negative gate bias stress according to annealing temperature was also investigated. While the Vth shifts dramatically after 1,000 s of both gate bias stresses, variations in the S.S are negligible. It suggests that electrons or holes are temporarily trapped in the gate insulator, the semiconductor, or the interface between both layers.

In this study, thickness shear mode piezoelectric devices for AE sensor with excellent displacement and sensitivity characteristics were simulated using ATILA FEM program, and then fabricated. Displacement and electro mechanical coupling factors of the piezoelectric devices were investigated. The simulation results showed that excellent displacement and electromechanical coupling factor was obtained when the ratio of Length/Thickness was 1. The piezoelectric device of L/T=1 exhibited the optimum values of fr=150 kHz, displacement= 6.23×10(-8)[m], k15= 0.598. The results show that the thickness shear mode piezoelectric device is a promising candidate for the application of AE sensor piezoelectric device.

Conductive SrMoO3 thin films were fabricated by RF magnetron sputtering with the powder-type sputtering target, and annealed for crystallization. When RTP (rapid thermal processing) in vacuum was applied, the fabricated thin films showed the mixed phases of SrMoO3 and SrMoO4, but SrMoO3 phase could be promoted by the lowering of the working pressure during deposition. In order to eliminate O2 gas during deposition and annealing, further lowering of the working pressure and furnace annealing in hydrogen atmosphere were tried. With the optimization of the deposition and annealing conditions, the thin film with nearly single-phase of SrMoO3 was obtained, and it showed good electrical conduction properties with a low resistivity of 2.5×10(-3)Ω·cm at room temperature.

In this paper, we have compared amorphous InGaZnO (a-IGZO) thin-film transistor (TFT) with the nano-crystalline embedded-IGZO (Nc-embedded-IGZO) TFT fabricated by solid-phase crystallization (SPC) technique. The field effect mobility (μFE) of Nc-embedded-IGZO TFT was 2.37 cm2/Vs and the subthreshold slope (S-factor) was 0.83 V/decade, which showed lower performance than those of a-IGZO TFT (μFE of a-IGZO was 9.67 cm2/Vs and S-factor was 0.19 V/decade). This results originated from generation of oxygen vacancies in oxide semiconductor and interface between gate insulator and semiconductor due to high temperature annealing process. However, the threshold voltage shift (△V(TH)) of Nc-embedded-IGZO TFT was 0.5 V, which showed 1 V less shift than that of a-IGZO TFT under constant current stress during 10(5) s. This was because there were additionally less increase of interface trap charges in Nc-embedded-IGZO TFT than a-IGZO TFT.

ZnO is an n-type semiconductor with a wide band gap near 3.37 eV. It was known that ZnO films with a resistivity of the order of 10(-4) Ωcm is not easy to obtain. 1, 3, and 5wt% Si element were added into ZnO in ordre to improve the electrical and optical characteristics. The Si-doped ZnO (SZO) was grown on a glass substrate by radio frequency (RF) magnetron sputtering at the temperature range from 100 to 500℃. X-ray diffraction (XRD) patterns of SZO film showed preferable crystal orientation of (002) plane. It was confirmed that the lowest resistivity of the SZO films was 2.44≠10(-3) Ωcm and SZO films were significantly influenced by the working temperature. The average transmittance of the films was over 80% in the visible ranges.

To investigate the effect of two-emission-layer structure on the emission characteristics of the phosphorescent white organic light-emitting diodes (PHWOLEDs), the PHWOLEDs with two different emission layers, blue EML(29 nm, FIrpic-doped mCP) and red EML(1 nm, Ir(pq)2acac-doped CBP)), following host-guest system were fabricated. The bi-layered blue EML was composed of mCP:FIrpic (20 nm, 7 vol.%) and mCP:FIrpic (9 nm, 7, 10, 15, 20, and 25 vol.%, respectively). When the concentration of FIrpic was increased from 7 to 15 vol.%, light emission luminance, current efficiency, and external quantum efficiency were increased. On the contrary, when the concentration of FIrpic was increased to more than 20 vol.%, light emission luminance, current efficiency, and external quantum efficiency were decreased. The PHWOLEDs with the bi-layered blue EML structure of mCP:FIrpic (20 nm, 7 vol.%) and mCP:FIrpic (9 nm, 15 vol.%) showed current efficiency of 29.7 cd/A and external quantum efficiency (EQE) of 16.6% at 1,000 cd/cm2.

Al-doped ZnO film on glass substrate is deposited by ALD in low temperature, using 4-step process (DEZ-H2O-TMA-H2O). To find out the optimal film condition for TCO material, we fabricate Al-doped ZnO films by increasing Al doping concentration at 100℃, so that the Al-doped film of 5 at% shows the lowest resistivity (1.057×10(-2) Ω·cm) and the largest grain size (38.047 nm). Afterwards, the electrical and physical characteristics in Al-doped films of 5 at% are also compared in accordance with increasing deposition temperature. All the films show the optical transmittance over 80% and the film deposited at 250℃ demonstrates the superior resistivity (1.237×10(-4) Ω·cm).

Currently in Korea, the simple catenary type overhead contact line system is being applied to both conventional lines and high speed lines of electric railway, and circulation current flowing into the catenary system frequently bring undesirable consequences. Namely, the connector wire has many problems according to a flow of excessive circulation current and arc current on catenary when an electric train runs at high speed. This paper presents the development and application of a real-time data acquisition system designed to measure the electrical characteristics of an overhead catenary system in electric railways. The developed system is capable of storing data of a 25 kV power source in a live wire state through a telemetry environment. The field test results show that the proposed technique and the developed system can be practically applied to measure characteristics of current of an overhead catenary system.

The conducting current of non-uniform plasma immersed electrode consists of ion current and secondary electron emission current caused by the impinging ion current. The ion current is determined by the ion dose passing through the sheath in front of electrode and the ion distribution in front of the electrode plays an important role in the secondary electron emission. The investigation of the distributed plasma and secondary electron effect on electrode ion current was carried out as the stainless steel electrode plugged with quartz tube was immersed in the inductively coupled Ar plasma using the antenna powered by 1 kw and the density profile was measured. After that, the negative voltage was applied by 1 kV∼6 kV to measure the conduction current for the analysis of ion current.

Based on first-principles LCAO method, we study the electronic and atomic structures of DNA nucleobases adenine (A), thymine (T), guanine (G), and cytosine (C) adsorbed on graphene surfaces. The π-π stacking interactions between graphene and nucleobases lead to the bilayer geometries similar to the Bernal stacked graphite. Through the density of states and charge density analyses, it is found that nucleobases are physisorbed on graphene by dispersive interactions with negligible charge exchange. Our calculations reproduce the atomic structures obtained in previous plane wave calculations accurately with much less computation, and well describe the delocalized π-π interactions in graphene-nucleobases system, indicating that the LCAO method is very efficient for investigating graphene-bio systems.

In this work, we designed and fabricated a multilayer thin film Pb(Zr,Ti)O(3) cantilever with a Si proof mass for low frequency vibration energy harvesting applications. A mathematical model of a multi-layer composite beam was derived and applied in a parametric analysis of the piezoelectric cantilever. Finally, the dimensions of the cantilever were determined for the resonant frequency of the cantilever. We fabricated a device with beam dimensions of about 4,930 μm × 450 μm × 12 μm, and an integrated Si proof mass with dimensions of about 1,410 μm × 450 μm × 450 μm. The resonant frequency, maximum peak voltage, and highest average power of the cantilever device were 84.5 Hz, 88 mV, and 0.166 μWat 1.0 g and 23.7 Ω, respectively. The dimensions of the cantilever were determined for the resonance frequency of the cantilever.

ABLB (alternate binaural loudness balance) test is one of the medical assessments to diagnose detailed lesion of sensory-neural hearing loss based on a recruitment phenomenon. However, current ABLB audiometry takes an operational model, so called face-to-face model, in which model one audiometrist can assess only one subject at a time. As a result, this face-to-face model leads to expensive audiometrist`s labor cost and lengthy wait when there exist many subjects. As a solution, this paper suggests an ABLB audiometry system supporting one-to-many model in which model an audiometrist enables to assess several subjects concurrently. By providing such capabilities as real-time transfer of assessment result, video monitoring of subject and video chat, this solution can provide same effect as face-to-face model but overcome weakness of the existing face-to-face model.