• Korean Journal of Materials Research
• /
• v.4 no.1
• /
• pp.63-74
• /
• 1994

The ultrathin oxide films less than 100$\AA$ were grown by thermal oxidation in $N_2O$ ambient to improve the controllability of thickness, thickness uniformity, process reproducibility and their electrical properties. Oxidation rate was reduced significantly at very thin region due to the formation of oxynitride layer in $N_2O$ ambient and moreover nitridation of the oxide layer was simultaneously accompanied during growth. The nitrogen incorporation in the grown oxide layer was characterized with the wet chemical etch-rate and ESCA analysis of the grown oxide layer. All the oxides thin films grown in $N_2O$, pure and dilute $O_2$ ambients show Fowler-Nordheim electrical conduction. The electrical characteristics of thin oxide films grown in $N_2O$ such as leakage current, electrical breakdown, interface trap density generation due to the injected electron and reliability were better than those in pure or dilute ambient. These improved properties can be explained by the fact that the weak Si-0 bond is reduced by stress relaxation during oxidation and replacement by strong Si-N bond, and thus the trap sites are reduced.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.11a
• /
• pp.235-235
• /
• 2003

The development of a buffer layer is an important issue for the second -generation wire, YBCO coated metal wire. The buffer layer demands not only on the prohibition of the reaction between YBCO and metal substrate, but also the proper lattice match and conductivity for high critical current density (Jc) of YBCO superconductor, In order to satisfy these demands, we suggested CaRuO3 as a useful candidate having that the lattice mismatches with Ni (200) and with YBCO are 8.2% and 8.0%, respectively. The CaRuO3 thin films were deposited on Ni substrates using various methods, such as e-beam evaporation and DC and RF magnetron sputtering. These films were investigated using SEM, XRD, pole-figure and AES. In e-beam evaporation, the deposition temperature of CaRuO3 was the most important since both hi-axial texturing and NiO formation between Ni and CaRuO3 depended on it. Also, the oxygen flow rate had i[n effect on the growth of CaRuO3 on Ni substrates. The optimal conditions of crystal growth and film uniformity were 400$^{\circ}C$, 50 ㎃ and 7 ㎸ when oxygen flow rate was 70∼100sccm In RF magnetron sputtering, CaRuO3 was deposited on Ni substrates with various conditions and annealing temperatures. As a result, the conductivity of CaRuO3 thin films was dependent on CaRuO3 layer thickness and fabrication temperature. We suggested the multi-step deposition, such as two-step deposition with different temperature, to prohibit the NiO formation and to control the hi-axial texture.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.11a
• /
• pp.24-25
• /
• 2006

SmBCO coated conductors were successfully fabricated using EDDC (Evaporation using Drum in Dual Chambers) deposition system that is a bath type co-evaporation system for fabrication of superconducting tape and divided into two chambers named evaporation chamber and reaction chamber. To obtain long and high quality superconducting coated conductor, it is very important to secure the uniformity of all the deposition parameters m the deposition system such as deposition temperature, oxygen partial pressure, compositional ratios and so on. Therefore, we investigated the distribution of the parameters along the axis of the drum m EDDC on which tapes were wound helically. When the temperature on the middle point of deposition zone was $700^{\circ}C$, that on the edge of deposition zone was $675^{\circ}C$. When the thickness of SmBCO layer on the middle point of deposition zone was 1063 nm, that on the edge of deposition zone was 899 nm. The partial pressure of oxygen was 5 mTorr in the reaction chamber while that was $7{\times}10^{-5}$Torr in the evaporation chamber. The composition ratio of Sm:Ba:Cu, that was measured by EDX, was very uniform along the axis of the drum. Under these deposition conditions, critical current distribution along the drum axis was 175 A/cm, 190A/cm, 217.5 A/cm, 182.5 A/cm, 175 A/cm with the interval of 9 cm between samples. It means that the EDDC system has the potential of fabricating (100m, 200A) class coated conductor.

• Hwankyungkyoyuk
• /
• v.10 no.2
• /
• pp.101-120
• /
• 1997

The objective of this research is to understand the current field and composition of environment related terminology used in middle and high school textbooks, to find out uniformity and relationship between them, and development for the future establishement and replacement in the environmental education, simultaneously. The results of this study are as follows: 1. The terms used in middle school textbooks were found out to be 334, while those used in high school were 717. Total terms used were 870(759 kinds) and those recorded in the environmental terminology dictionary were 362 including synonyms. 2. Of those 870, 211 terms (24.25%) which were the same words have been used in interlinked connection with the Middle and High schools. While 136 terms(15.63%) have been used in the only middle, and 524 terms(60.23%) have been used in the only high schools. In middle and high school environmental text books 211 (24.25%) terms were the same interlinked terms. Of those extracted terms, 136(15.63%) were used in the middle school 'environmental' textbooks and in high school, 524(60.23%) were used in 'environmental science' book. These results shows that there is big gap between middle and high school contents and we will need more consideration in selecting the terms and better substance. 3. The same terminologies used in both middle and high schools were total number of 676. In those terms 257 kinds(76.26%) were used in middle school 'environmental' text books, and 563 kinds(78.52%) in high school 'environmental science' text books. Here are some details : 1) Terms used as same meaning but different in expression in middle school: 83 kinds, 192 terms (11.99%). 2) Differently expressed in the same text book : in middle school - 20 kinds(2.64%) in high school - 61 kinds(8.04%) 3) Differently expressed terms between middle and high school: 51 kinds(6.72%) 4) Same meaning in 3 expressions or more : 19 kinds 4. Of the examined terms 362(including 43 synonyms) were defined in environmental dictionary which is 41.8% of the total words. In the future specialization in utmost fields will be needed 5. When dividing those examined terms according to the middle and high school curriculum, the most terms were used in nature and pollution fields following environmental preserving, artificial environment, and environmenatal counterplan. In middle schools the most used terms were in the field of environment pollution, preservation, counterplan, and sanitation. These results reflects the education goals and objectives of middle schools. But for the middle school 'environment' curriculum moret uniform distribution are needed and for the high schools' 'environmental science' program, the fields in artificial environment, industrization, urbanization, and sanitation should be intensified.

• Hwankyungkyoyuk
• /
• v.10 no.2
• /
• pp.121-132
• /
• 1997

The objective of this research is to understand the current field and composition of environment related terminology used in middle and high school textbooks, to find out uniformity and relationship between them, and development for the future establishement and replacement in the environmental education, simultaneously. The results of this study are as follows: 1. The terms used in middle school textbooks were found out to be 334, while those used in high school were 717. Total terms used were 870(759 kinds) and those recorded in the environmental terminology dictionary were 362 including synonyms. 2. Of those 870, 211 terms(24.25%) which were the same words have been used in interlinked connection with the Middle and High schools. While 136 terms(15.63%) have been used in the only middle, and 524 terms(60.23%) have been used in the only high schools. In middle and high school environmental tort books 211 (24.25%) terms were the same interlinked terms. Of those extracted terms, 136(15.63%) were used in the middle school 'environmental' textbooks and in high school, 524(60.23%) were used in 'environmental science' book. These results shows that there is big gap between middle and high school contents and we will need mere consideration in selecting the terms and better substance. 3. The same terminologies used in both middle and high schools were total number of 676. In those terms 257 kinds(76.26%) were used in middle school 'environmental' text books, and 563 kinds(78.52%) in high school 'environmental science' text books. Here are some details : 1) Terms used as same meaning but different in expression in middle school : 83 kinds, 192 terms(11.99%). 2) Differently expressed in the same tort book in kiddie school - 20 kinds(2.64%) in high school - 61 kinds(8.04%) 3) Differently expressed terms between middle and high school : 51 kinds(6.72%) 4) Same meaning in 3 expressions or more : 19 kinds 4. Of the examined terms 362(including 43 synonyms) were defined in environmental dictionary which is 41.8% of the total words. In the future specialization in utmost fields will be needed 5. When dividing those examined terms according to the middle and high school curriculum, the most terms were used in nature and pollution fields following environmental preserving, artificial environment and environmenatal counterplan. In middle schools the most used terms were in the field of environment pollution, preservation, counterplan, and santiation. There results reflects the education goals and objectives of middle schools. But for the middle school 'environment' curriculum moret uniform distribution are needed and for the high schools' 'enironmental science' program, the fields in artificial environment, industrization, urbanization, and sanitation should be intensified.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.11-11
• /
• 2010

Thin-film-transistors (TFTs) that can be deposited at low temperature have recently attracted lots of applications such as sensors, solar cell and displays, because of the great flexible electronics and transparent. Transparent and flexible transistors are being required that high mobility and large-area uniformity at low temperature [1]. But, unfortunately most of TFT structures are used to be $SiO_2$ as gate dielectric layer. The $SiO_2$ has disadvantaged that it is required to high driving voltage to achieve the same operating efficiency compared with other high-k materials and its thickness is thicker than high-k materials [2]. To solve this problem, we find lots of high-k materials as $HfO_2$, $ZrO_2$, $SiN_x$, $TiO_2$, $Al_2O_3$. Among the High-k materials, $Al_2O_3$ is one of the outstanding materials due to its properties are high dielectric constant ( ~9 ), relatively low leakage current, wide bandgap ( 8.7 eV ) and good device stability. For the realization of flexible displays, all processes should be performed at very low temperatures, but low temperature $Al_2O_3$ grown by sputtering showed deteriorated electrical performance. Further decrease in growth temperature induces a high density of charge traps in the gate oxide/channel. This study investigated the effect of growth temperatures of ALD grown $Al_2O_3$ layers on the TFT device performance. The ALD deposition showed high conformal and defect-free dielectric layers at low temperature compared with other deposition equipments [2]. After ITO was wet-chemically etched with HCl : $HNO_3$ = 3:1, $Al_2O_3$ layer was deposited by ALD at various growth temperatures or lift-off process. Amorphous InGaZnO channel layers were deposited by rf magnetron sputtering at a working pressure of 3 mTorr and $O_2$/Ar (1/29 sccm). The electrodes were formed with electron-beam evaporated Ti (30 nm) and Au (70 nm) bilayer. The TFT devices were heat-treated in a furnace at $300^{\circ}C$ and nitrogen atmosphere for 1 hour by rapid thermal treatment. The electrical properties of the oxide TFTs were measured using semiconductor parameter analyzer (4145B), and LCR meter.

• Applied Chemistry for Engineering
• /
• v.29 no.5
• /
• pp.510-518
• /
• 2018

Recently, lots of interests have been concentrated on the scrubber system that abates waste gases produced from semiconductor manufacturing processes. An effective design of the thermal decomposition reactor inside a scrubber system is significantly important since it is directly related to the removal performance of pollutants and overall stabilities. In the present study, a computational fluid dynamics (CFD) analysis was conducted to figure out the thermal and flow characteristics inside the reactor of wet scrubber. In order to verify the numerical method, the temperature at several monitoring points was compared to that of experimental results. Average error rates of 1.27~2.27% between both the results were achieved, and numerical results of the temperature distribution were in good agreement with the experimental data. By using the validated numerical method, the effect of the reactor geometry on the heat transfer rate was also taken into consideration. From the result, it was observed that the flow and temperature uniformity were significantly improved. Overall, our current study could provide useful information to identify the fluid behavior and thermal performance for various scrubber systems.

• Journal of the Microelectronics and Packaging Society
• /
• v.10 no.2
• /
• pp.1-5
• /
• 2003

In this project, the efficiency of localized heating for micro systems packaging is developed by using a forced potential scheme microheater. Less than 0.2 Mpa contact pressure was used for bonding with a 200 mA current input for $50{\mu}m$ width, $2{\mu}m$ height and $8mm{\times}8mm$, $5mm{\times}5mm$, $3mm{\times}3mm$ sized phosphorus-doped poly-silicon microheater. The temperature can be raised at the bonding region to $800^{\circ}C$, and it was enough to achieve a strong and reliable bonding in 3 minutes. The IR camera test results show improved uniformity in heat distribution compared with conventional microheaters. For performing the gross leak check, IPA (Isopropanol Alcohol) was used. Since IPA has better wetability than water, it can easily penetrate small openings, and is more suitable for conducting a gross leak check. The pass ratio of bonded dies was 67%, for conventional localized heating, and 85% for our newly developed FP scheme. The bonding strength was more than 25Mpa for FP scheme packaging, which shows that FP scheme can be a good candidate for micro-scale hermetic packaging.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.324-325
• /
• 2014

Quantum wells infrared photodetectors (QWIPs) have been used to detect infrared radiations through the principle based on the localized stated in quantum wells (QWs) [1]. The mature III-V compound semiconductor technology used to fabricate these devices results in much lower costs, larger array sizes, higher pixel operability, and better uniformity than those achievable with competing technologies such as HgCdTe. Especially, GaAs/AlGaAs QWIPs have been extensively used for large focal plane arrays (FPAs) of infrared imaging system. However, the research efforts for increasing sensitivity and operating temperature of the QWIPs still have pursued. The modification of heterostructures [2] and the various fabrications for preventing polarization selection rule [3] were suggested. In order to enhance optical performances of the QWIPs, double barrier quantum well (DBQW) structures will be introduced as the absorption layers for the suggested QWIPs. The DBWQ structure is an adequate solution for photodetectors working in the mid-wavelength infrared (MWIR) region and broadens the responsivity spectrum [4]. In this study, InGaAs/GaAs/AlGaAs double barrier quantum well infrared photodetectors (DB-QWIPs) are successfully fabricated and characterized. The heterostructures of the InGaAs/GaAs/AlGaAs DB-QWIPs are grown by molecular beam epitaxy (MBE) system. Photoluminescence (PL) spectroscopy is used to examine the heterostructures of the InGaAs/GaAs/AlGaAs DB-QWIP. The mesa-type DB-QWIPs (Area : $2mm{\times}2mm$) are fabricated by conventional optical lithography and wet etching process and Ni/Ge/Au ohmic contacts were evaporated onto the top and bottom layers. The dark current are measured at different temperatures and the temperature and applied bias dependence of the intersubband photocurrents are studied by using Fourier transform infrared spectrometer (FTIR) system equipped with cryostat. The photovoltaic behavior of the DB-QWIPs can be observed up to 120 K due to the generated built-in electric field caused from the asymmetric heterostructures of the DB-QWIPs. The fabricated DB-QWIPs exhibit spectral photoresponses at wavelengths range from 3 to $7{\mu}m$. Grating structure formed on the window surface of the DB-QWIP will induce the enhancement of optical responses.

• Journal of the Korea Computer Industry Society
• /
• v.8 no.2
• /
• pp.97-102
• /
• 2007

[ $CO_2$ ] laser sees that is most suitable to get this effect through minimum formation damage and advantage that is root enemy of effect that happen in minimum cellular tissue depth of 0.1mm is stable living body organization or internal organs institution. Formation damage by ten can be related in formation's kind or energy density, length of evaporation time. If shorten evaporation time, surroundings cellular thermal damage 200 - because happen within 400um laser beam in rain focus sacred ground surroundings cellular tissue without vitiation me by evaporation Poe of very small floor as is clean steam can . Application is possible to vulva cuticle cousins by a paternal aunt quantity, uterine cancer, cuticle tumor by laser system that $CO_2$ laser gets into standard in obstetrics and gynecology application. Because effect that super pulse output is ten enemies of laser if uniformity one pulse durations are short almost is decreased, most of all pulse module special quality of Pulse style $CO_2$ laser for obstetrics and gynecology mode stabilization by weight very, in this research to get into short pulse duration and higher frequency density, do switching by high frequency in DC-DC Converter output DC's ripple high frequency to be changed, high frequency done current ripple amount of condenser for output filter greatly reduce can . Ripple of output approximately to Zero realization applying possible inductor realization through a special quality experiment do.