• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.16-19
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• 2002

(Ba,Sr)TiO3(BST) thin film is an attractive material for the application in high-density dynamic random access memories (DRAMs) because of the high relative dielectric constant and small variation in dielectric properties with frequency. In this study, (Ba0.6,Sr0.4)TiO3 thin films on Pt/Ti/SiO2/Si substrates were deposited by a sol-gel method and the CF4/Ar inductively coupled plasma (ICP) etching behavior of BST thin films had been investigatedby varying the process parameters such as chamber pressure, ICP power, and substrate bias voltage. To analysis the composition of surface residue following etching BST films etched with different Ar/CF4 gas mixing ratio were investigated using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometer (SIMS).

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.247-253
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• 2018

We examined the characteristics of indium tin zinc oxide (ITZO) thin film transistors (TFTs) on polyimide (PI) substrates for next-generation flexible display application. In this study, the ITZO TFT was fabricated and analyzed with a SiOx/SiNx gate insulator deposited using plasma enhanced chemical vapor deposition (PECVD) below $350^{\circ}C$. X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) results revealed that the oxygen vacancies and impurities such as H, OH and $H_2O$ increased at ITZO/gate insulator interface. Our study suggests that the hydrogen related impurities existing in the PI and gate insulator were diffused into the channel during the fabrication process. We demonstrate that these impurities and oxygen vacancies in the ITZO channel/gate insulator may cause degradation of the electrical characteristics and bias stability. Therefore, in order to realize high performance oxide TFTs for flexible displays, it is necessary to develop a buffer layer (e.g., $Al_2O_3$) that can sufficiently prevent the diffusion of impurities into the channel.

• Journal of the Korean earth science society
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• v.26 no.2
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• pp.129-136
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• 2005

Continued observation of ARGO floats for years(about 4 years) makes the conductivity sensor more vulnerable to fouling by marine life and associated drift in salinity measurements. In this paper, we address this issue by making use of floats deployed in different years. Floats deployed in the East Sea and the Indian Ocean are examined to find out float-to-float match-ups in such a way that an older float pops up simultaneously with a newer deployment (with tolerable space-time difference). A time difference of less than five days and space difference of less than 100km are considered for the match-up data sets. For analysis of the salinity drift under the stable water mass, observations of the floats from deepest water masses have been used. From the cross-check of ARGO floats in the East Sea and the Indian Ocean, it is found that there is a systematic drift in the older float compared to later deployments. All drift results, consistently show negative bias indicating the typical nature of drift from fouled sensors. However, the drift is much less than 0.01, the specified accuracy of ARGO program.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.915-918
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• 2010

In this work, the etching characteristics of ZnO thin films were investigated using an inductively coupled plasma(ICP) of HBr/Ar/$CHF_3$ gas mixtures. The plasma characteristics were analyzed by a quadrupole mass spectrometer (QMS) and double langmuir probe (DLP). The surface reaction of the ZnO thin films was investigated using X-ray photoelectron spectroscopy (XPS). The etch rate of ZnO was measured as a function of the $CHF_3$ mixing ratio in the range of 0-15% in an HBr:Ar=5:2 plasma at a fixed gas pressure (6mTorr), input power (700 W), bias power (200 W) and total gas flow rate(50sccm). The etch rate of the ZnO films decreased with increasing $CHF_3$ fraction due to the etch-blocking polymer layer formation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.2
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• pp.106-111
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• 2001

The applicability of near infrared reflectance spectroscopy(NIRS) was tested to determine the protein and oil contents in ground soybean [Glycine max (L.) Merr.] seeds. A total of 189 soybean calibration samples and 103 validation samples were used for NIRS equation development and validation, respectively. In the NIRS equation of protein, the most accurate equation was obtained at 2, 8, 6, 1(2nd derivative, 8 nm gap, 6 points smoothing and 1 point second smoothing) math treatment condition with SNV-D (Standard Normal Variate and Detrend) scatter correction method and entire spectrum by using MPLS (Modified Partial Least Squares) regression. In the case of oil, the best equation was obtained at 1, 4, 4, 1 condition with SNV-D scatter correction method and near infrared (1100-2500nm) region by using MPLS regression. Validation of these NIRS equations showed very low bias (protein:-0.016%, oil : -0.011 %) and standard error of prediction (SEP, protein: 0.437%, oil: 0.377%) and very high coefficient of determination ($R^2$, protein: 0.985, oil : 0.965). Therefore, these NIRS equation seems reliable for determining the protein and oil content, and NIRS method could be used as a mass screening method of soybean seed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.996-1002
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• 2000

Ferroelectric (Ba, Sr) TiO$_3$(BST) thin films have attracted much attention for use in new capacitor materials of dynamic random access memories (DRAMs). In order to apply BST to the DRAMs, the etching process for BST thin film with high etch rate and vertical profile must be developed. However, the former studies have the problem of low etch rate. In this study, in order to increase the etch rate, BST thin films were etched with a magnetically enhanced inductively coupled plasma(MEICP) that have much higher plasma density than RIE (reactive ion etching) and ICP (inductively coupled plasma). Experiment was done by varying the etching parameters such as CF$_4$/(CF$_4$+Ar) gas mixing ratio, rf power, dc bias voltage and chamber pressure. The maximum etch rate of the BST films was 170nm/min under CF$_4$/CF$_4$+Ar) of 0.1, 600 W/-350 V and 5 mTorr. The selectivities of BST to Pt and PR were 0.6 and 0.7, respectively. Chemical reaction and residue of the etched surface were investigated with X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS).

• Journal of Korean Society of Steel Construction
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• v.12 no.1 s.44
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• pp.83-91
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• 2000

The first Procedure to identify structural system by using measured data is transformation of data to frequency domain and try to recognize modal characteristics in graphical condition. Those methods are doubted about the reliability to the civil structures, especially bridges which has coupled and close modal characteristics. In this paper, feasibility of time domain modal Identification methods were examined and applied double least square method to overcome bias characteristics of the identification methods. To show the advantage of proposed method, simulation were carried out for mass-spring model. And to examine the usage of the method in realistic case, sensitivity of the methods to noise was performed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.11
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• pp.933-938
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• 2002

(Ba,Sr)TiO$_{4}$ (BST) thin films on Pt/Ti/SiO$_{2}$/Si substrates were deposited by a sol-gel method and the etch characteristics of BST thin films have been investigated as a function of gas mixing ratio. The maximum etch rate of the BST films was 440 $AA$/min under such conditions as: CF$_{4}$(CF$_{4}$＋Ar) of 0.2, RF-power of 700 W, DC-bias voltage of -200 V, pressure of 15 mTorr and substrate temperature of 30 $^{circ}C$. The selectivities of BST to Pt, SiO$_{2}$ and PR were 0.38, 0.25 and 0.09, respectively. In the XPS (X-ray photoelectron spectroscopy) analysis, Barium (Ba) and Strontium (Sr) component in BST thin films formed low volatile compounds such as BaFx, SrFx, which are forms by the chemical reaction with F atoms and is removed by Ar ion bombardment. Titanium (Ti) is removed by chemical reaction such as TiF with ease. The result of secondary ion mass spectrometry (SIMS) analysis confirmed the existence of the BaFx, SrFK, TiFx.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.8
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• pp.727-732
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• 2008

In this work, the etch characteristics of $VO_2$ thin films were investigated using inductively coupled plasma (ICP) of $Cl_2/Ar$ gas mixtures. To analyze the plasma characteristics, a quadrupole mass spectrometer (QMS), an optical emission spectroscopy (OES), and a Langmuir probe measuring system were used. The surface reaction of the $VO_2$ thin films was investigated using X-ray photoelectron spectroscopy (XPS). It was found that an increase in Ar fraction in the $Cl_2/Ar$ plasma at fixed gas pressure, input power, and bias power resulted in increasing $VO_2$ etch rate which reached a maximum value of 87.6 nm/min at 70-75 % Ar. It was confirmed that the etch rate of the $VO_2$ films was mainly controlled by the ion flux. On the basis of measuring results, we will discuss possible etching mechanism of $VO_2$ film in the $Cl_2/Ar$ plasma.

• Journal of the Korean Institute of Telematics and Electronics
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• v.10 no.3
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• pp.1-9
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• 1973

Gallium phosphide light emitting diode (LED) has been fabricated first time for pilot lamp and numeric display purposes. Bright red light is obtained in forward bias at very low current of one to five mA. A typical p-n junction is formed by liquid phase epitaxial growth on a n-type gallium physphide substrate. The crystal growth is achieved at about 1300$^{\circ}$K after the equilibrium of the gallium solution followed by tipping operation. The ohmic contact is made by wire bonding by thermal compression technique. The entire process is well fit for laboratory scale to fabricate a few hundred diodes for mainly demonstration purpose. For mass production, a large sum of the capital investment is required. The great merit of gallium phosphide LED is at low current operation, and green light emission is also obtainable by nitrogen doping.