• Title/Summary/Keyword: Defect concentration

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Effects of electronic energy deposition on pre-existing defects in 6H-SiC

  • Liao, Wenlong;He, Huan;Li, Yang;Liu, Wenbo;Zang, Hang;Wei, Jianan;He, Chaohui
    • Nuclear Engineering and Technology
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    • v.53 no.7
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    • pp.2357-2363
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    • 2021
  • Silicon carbide is widely used in radiation environments due to its excellent properties. However, when exposed to the strong radiation environment constantly, plenty of defects are generated, thus causing the material performance downgrades or failures. In this paper, the two-temperature model (2T-MD) is used to explore the defect recovery process by applying the electronic energy loss (Se) on the pre-damaged system. The effects of defect concentration and the applied electronic energy loss on the defect recovery process are investigated, respectively. The results demonstrate that almost no defect recovery takes place until the defect density in the damage region or the local defect density is large enough, and the probability of defect recovery increases with the defect concentration. Additionally, the results indicate that the defect recovery induced by swift heavy ions is mainly connected with the homogeneous recombination of the carbon defects, while the probability of heterogeneous recombination is mainly dependent on the silicon defects.

Determination of Alpha Defect Center in the Nature Using EPR Spectroscopy

  • Cho, Young-Hwan;Hyun, Sung-Pil;Pilsoo Hahn
    • Journal of the Korean Magnetic Resonance Society
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    • v.5 no.1
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    • pp.13-18
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    • 2001
  • Natural alpha radiation produced a stable defect center to certain minerals. Electron Paramagnetic Resonance(EPR) spectroscopy is a powerful tool f3r quantifying this defect center. EPR method has been applied to trace alpha-radiation effect around the uranium ore deposit. The results show that EPR technique can be used to measure rapidly and nondestructively the defect center produced by natural alpha radiation. In general, a good correlation was achieved between defect center concentration and actinide elements(U, Th). These results imply that the concentration of defect center is dependent on the alpha radiation dose over long time scale.

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A Study of defect distribution and profiles of MeV implanted phosphorus in silicon (실리콘에 MaV로 이온주입된 인의 결함분포와 profile에 관한 연구)

  • 정원채
    • Electrical & Electronic Materials
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    • v.10 no.9
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    • pp.881-888
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    • 1997
  • This study demonstrats the profiles of phosphorus ions in silicon by MeV implantation(1∼3 MeV). Implanted profiles could be measured by SIMS(Cameca 4f) and compared with simulation results(TRIM program and analytical description method only using on Pearson function). The experimental result in the peak concentration region has a little bit deviation from simulation data. By RBS and Channeling measurements the defect distribution of implanted samples could be measured and spectrum are calibrated depth with RUMP simulation By XTEM measurement the thickness of defect zone also could be measured. Finally thermal annealing for the electrical activation of implanted ions carried out by RTA(rapid thermal annealing). The concentration-depth profiles after heat treatment was measured by SR(spreading resistance)-method.

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Defect Structure, Nonstoichiometry and Nonstoichiometry Relaxation of Complex Oxides

  • Yoo, Han-Ill
    • Journal of the Korean Ceramic Society
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    • v.44 no.12
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    • pp.660-682
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    • 2007
  • An SOFC consists of all ceramic complex oxides each with different electrochemical-property requirements. These requirements, in principle, can be made met to a great extent by controlling or tailoring the defect structure of the oxide. This paper reviews the defect structure, nonstoichiometry as a measure of the total defect concentration, and the defect relaxation kinetics of complex oxides that are currently involved in a variety of growing applications today.

Effect of Dopants on the Microwave Dielectric Properties of $(1-x)MgTiO_3-xCaTiO_3$ Ceramics (불순물 첨가에 따른 $(1-x)MgTiO_3-xCaTiO_3$ 세라믹스의 마이크로웨이브 유전특성변화)

  • 우동찬;이희영;한주환;김태홍;최태구
    • Journal of the Korean Ceramic Society
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    • v.34 no.8
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    • pp.843-853
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    • 1997
  • The effect of dopant on microwave dielectric properties of (1-x)MgTiO3-xCaTiO3 ceramics, known to be used as microwave dielectric resonators for global positioning system and personal communication system, has been analyzed in terms of variations in defect concentrations and microstructural features with its addition. The addition of dopants was revealed to result in a significant change in the microstructure as well as defect concentration of the ceramics. For instance, the quality factor is proportional to sintered density of the ceramics by inversely proportional to grain size as well as vacancy concentration. Accordingly, it is believed that the dopant effect on the microwave dielectric properties should be separately analyzed with either microstructural change or the change in vacancy concentration.

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The effect of deep level defects in SiC on the electrical characteristics of Schottky barrier diode structures (깊은 준위 결함에 의한 SiC SBD 전기적 특성에 대한 영향 분석)

  • Lee, Geon-Hee;Byun, Dong-Wook;Shin, Myeong-Cheol;Koo, Sang-Mo
    • Journal of IKEEE
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    • v.26 no.1
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    • pp.50-55
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    • 2022
  • SiC is a power semiconductor with a wide bandgap, high insulation failure strength, and thermal conductivity, but many deep-level defects. Defects that appear in SiC can be divided into two categories, defects that appear in physical properties and interface traps that appear at interfaces. In this paper, Z1/2 trap concentration 0 ~ 9×1014 cm-3 reported at room temperature (300 K) is applied to SiC substrates and epi layer to investigate turn-on characteristics. As the trap concentration increased, the current density, Shockley-read-Hall (SRH), and Auger recombination decreased, and Ron increased by about 550% from 0.004 to 0.022 mohm.

Electrical Characteristics of Solution Processed DAL TFT with Various Mol concentration of Front channel

  • Kim, Hyunki;Choi, Byoungdeog
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.211.2-211.2
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    • 2015
  • In order to investigate the effect of front channel in DAL (dual active layer) TFT (thin film transistor), we successfully fabricated DAL TFT composed of ITZO and IGZO as active layer using the solution process. In this structure, ITZO and IGZO active layer were used as front and back channel, respectively. The front channel was changed from 0.05 to 0.2 M at fixed 0.3 M IGZO of back channel. When the mol concentration of front channel was increased, the threshold voltage (VTH) was increased from 2.0 to -11.9 V and off current also was increased from 10-12 to 10-11. This phenomenon is due to increasing the carrier concentration by increasing the volume of the front channel. The saturation mobility of DAL TFT with 0.05, 0.1, and 0.2 M ITZO were 0.45, 4.3, and $0.65cm2/V{\cdot}s$. Even though 0.2 M ITZO has higher carrier concentration than 0.05 and 0.1 M ITZO, the 0.1 M ITZO/0.3 M IGZO DAL TFT has the highest saturation mobility. This is due to channel defect such as pores and pin-holes. These defect sites were created during deposition process by solvent evaporation. Due to these defect sites, the 0.1 M ITZO/0.3 M IGZO DAL TFT shows the higher saturation mobility than that of DAL TFT with front channel of 0.2 M ITZO.

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The Variation of Stress Concentration Factor and Crack Initiation Behavior on the Hole Defects Around the Rivet Hole in a Aircraft Materials (항공재료 리벳홀에 인접한 원공결함의 위치에 따른 응력집중계수의 변화와 균열발생거동)

  • Song, Sam-Hong;Kim, Cheol-Woong;Kim, Tae-Soo;Hwang, Jin-Woo
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.381-388
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    • 2003
  • The material deficiencies in the form of pre-existing defects can initiated cracks and fractures. The stress distribution and fatigue crack initiation life of engineering materials may be associated with the size, the shape and the relative location of defects contained in the component. The objective of this study is to investigate the effect of arbitrarily located hole defect around the rivet hole of a wing section in monolithic aluminum and Al/GFRP laminates under cyclic bending moment during a service load. The stress distribution and the fatigue crack initiation behavior near a rivet hole of on the relationships between stress concentration factor ($K_t$) and relative position of defects were considered. The test results indicated the features of different stress field. Therefore, the stress concentration factor ($K_t$) and the fatigue crack initiation behavior was illustrated different behavior according to each position of hole defect around the rivet hole in monolithic aluminum and Al/GFRP laminates.

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Finite Element Based Stress Concentration Factors for Pipes with Local Wall Thinning (유한요소해석을 이용한 국부 감육배관에 대한 응력집중계수 제시)

  • Son, Beom-Goo;Kim, Yun-Jae;Kim, Young-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.7
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    • pp.1014-1020
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    • 2004
  • The present work complies the elastic stress concentration factor for a pipe with local wall thinning, based on detailed three-dimensional elastic FE analysis. To cover practically interesting cases, a wide range of pipe and defect geometries are considered, and both internal pressure and global bending are considered. Resulting values of stress concentration factors are tabulated for practical use, and the effect of relevant parameters such as pipe and defect geometries on stress concentration factors are discussed. The present results would provide valuable information to estimate fatigue damage of the pipe with local wall thinning under high cycle fatigue.

Thermal Properties of Diamond Films Deposited by Chemical Vapor Depositon

  • Chae, Hee-Baik;Baik, Young-Joon
    • The Korean Journal of Ceramics
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    • v.3 no.1
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    • pp.29-33
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    • 1997
  • Four diamond films were deposited by the microwave plasma assisted chemical vapor deposition method varying CH4 concentration from 2.5 to 10% in the feeding gases. Thermal conductivity was measured on these free standing films by the steady state method from 80 K to 400K. They showed higher thermal conductivity as the film deposited with lower methane concentration. One exception, 7.79% methane concentration deposited film, was observed to be the highest thermal conductivity. Phonon scattering processes were considered to analyze the thermal conductivity with the full Callaway model. The grain size and the concentration of the extended and the point defects were used as the fitting parameters. Microstructure of diamond films was investigated with the scanning electron microscopy and Raman spectroscopy.

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