• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.113-114
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• 2007

Hole mobility characteristics of single surface channel and dual channel Si/SiGe structure are compared, where the former one consists of a relaxed SiGe buffer layer and a tensile strained Si layer on top, and for dual channel structure a compressively strained SiGe layer is inserted between them. Due to the difference of hole mobility enhancement factors of layers between them, hole mobility characteristics with respect to the Si cap thickness shows the opposite tend. Hole mobility increases with thicker Si cap for single channel structure, whereas it decreases with thicker Si cap for dual channel structure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1250-1252
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• 1993

Enhancement mode n-channel TFT leakage current(off current : $V_G<0$) that is little agreement on the conduction mechanism is major disadvantage of poly-silicon TFT in practical use, characteristic analysis and model ing. In this paper, new modeling of leakage current is proposed. The activation energy of leakage current, which is dependent on gate voltage, and leakage current dependent on poly silicon thickness are plausibly explained with this model. This model indicate that the reduction of leakage current is attributable to a decrease of maximum laterial electric field strength in the drain depletion region and to the density of trap.

• Steel and Composite Structures
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• 제34권2호
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• pp.289-297
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• 2020

In the present research post-buckling of a cut out plate reinforced through carbon nanotubes (CNTs) resting on an elastic foundation is studied. Material characteristics of CNTs are hypothesized to be altered within thickness orientation which are calculated according to Mori-Tanaka model. For modeling the system mathematically, first order shear deformation theory (FSDT) is applied and using energy procedure, the governing equations can be derived. With respect to Rayleigh-Ritz procedure as well as Newton-Raphson iterative scheme, the motion equations are solved and therefore, post-buckling behavior of structure will be tracked. Diverse parameters as well as their reactions on post-buckling paths focusing cut out measurement, CNT's volume fraction and agglomeration, dimension of plate and an elastic foundation are investigated. It is revealed that presence of a square cut out can affect negatively post-buckling behavior of structure. Moreover, adding nanocompsits in the matrix leads to enhancement of post-buckling response of system.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.229-229
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• 2003

Enhancement of the exchange bias and optimization of the structure have been the focus that many researchers studied, recently [1]. In this report, magnetic properties of MTJs with structure of Si/Ta (5)/Cu (10)/ Ta (5)/ Ni$\sub$80/Fe$\sub$20/ Cu (5)/ Mn$\sub$75Ir$\sub$25/ (10)/ Co$\sub$70/Fe$\sub$30/ (2.5)/ Al-O (1.5)/ Co$\sub$70/Fe$\sub$30/ (2.5)/ Ni$\sub$80/Fe$\sub$20/ (t)/ Ta (5) (t=0,10, 30, 60 and 100 nm, respectively) were investigated. The relationship between the structure and magnetic parameters of interfacial exchange coupling and interlayer coupling in as-deposited and annealed junctions was studied. The temperature dependence of exchange coupling was considered.

• 대한전자공학회논문지SD
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• 제41권10호
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• pp.1-7
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• 2004

SOI 구조에서 형성된 MOS 트랜지스터의 장점과 strained Si에서 전자의 이동도가 향상되는 효과를 동시에 고려하기 위해 buried oxide(BOX)층과 Top Si층 사이에 Ge을 삽입하여 strained Si/relaxed SiGe/SiO₂Si 구조를 형성하고 strained Si fully depletion(FD) n-MOSFET를 제작하였다. 상부 strained Si층과 하부 SiGe층의 두께의 합을 12.8nm로 고정하고 상부 strained Si 층의 두께에 변화를 주어 두께의 변화가 electron mobility에 미치는 영향을 분석하였다. Strained Si/relaxed SiGe/SiO2/Si (strained Si/SGOI) 구조위의 FD n-MOSFET의 전자 이동도는 Si/SiO₂/Si (SOI) 구조위의 FD n-MOSFET 에 비해 30-80% 항상되었다. 상부 strained Si 층과 하부 SiGe 층의 두께의 합을 12.8nm 로 고정한 shrined Si/SGOI 구조 FD n-MOSFET에서 상부층 strained Si층의 두께가 감소하면 하부층 SiGe 층 두께 증가로 인한 Ge mole fraction이 증가함에 의해 inter-valley scattering 이 감소함에도 불구하고 n-channel 층의 전자이동도가 감소하였다. 이는 strained Si층의 두께가 감소할수록 2-fold valley에 있는 전자가 n-channel 층에 더욱더 confinement 되어 intra-valley phonon scattering 이 증가하여 전자 이동도가 감소함이 이론적으로 확인되었다.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1056-1063
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• 2006

10 nm-Ni/l nm-Ir(poly)Si과 10 nm-$Ni_{50}Co_{50}$/(poly)Si 구조의 박막을 열증착기로 준비하고 쾌속열처리기로 40초간 $300{\sim}1200^{\circ}C$ 온도 범위에서 실리사이드화 시켰다. 이들의 실리사이드 온도에 따른 면저항, 미세구조와 두께, 생성상, 화학조성과 표면조도의 변화를 사점면저항 측정기와 이온빔현미경, X선 회절기, 오제이 분석기, 주사탐침현미경을 써서 확인하였다. Ir과 Co의 혼입에 따라 기존의 $700^{\circ}C$에 한정된 NiSi에 비해 단결정, 다결정 실리콘 기판에서의 저저항 안정 구간이 각각 $1000^{\circ}C$, $850^{\circ}C$로 향상되었다. 이때의 실리사이드층의 두께도 20$\sim$50 nm로 나노급 공정에 적합하였다. Ir과 Co의 첨가는 단결정 기판에서의 니켈실리사이드의 고저항 $NiSi_2$로의 변태를 방지하였고, 다결정 기판에서 고온에서의 고저항은 고저항 상의 출현과 실리콘층과의 혼합과 도치현상이 발생한 것이 이유였다. Ir의 첨가는 특히 최종 실리사이드 표면온도를 3 nm 이내로 유지시키는 장점이 있었다 Ir과 Co를 첨가한 니켈실리사이드는 기존의 니켈실리사이드의 열적 안정성을 향상시켰고 나노급 디바이스에 적합한 물성을 가짐을 확인하였다.

• Korean Journal of Radiology
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• 제24권4호
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• pp.305-312
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• 2023

Objective: Chronic enteropathy associated with SLCO2A1 gene (CEAS) is a recently recognized disease. We aimed to evaluate the enterographic findings of CEAS. Materials and Methods: Altogether, 14 patients with CEAS were confirmed based on known SLCO2A1 mutations. They were registered in a multicenter Korean registry between July 2018 and July 2021. Nine of the patients (37.2 ± 13 years; all female) who underwent surgery-naïve-state computed tomography enterography (CTE) or magnetic resonance enterography (MRE) were identified. Two experienced radiologists reviewed 25 and 2 sets of CTE and MRE examinations, respectively, regarding the small bowel findings. Results: In initial evaluation, eight patients showed a total of 37 areas with mural abnormalities in the ileum on CTE, including 1-4 segments in six and > 10 segments in two patients. One patient showed unremarkable CTE. The involved segments were 10-85 mm (median, 20 mm) in length, 3-14 mm (median, 7 mm) in mural thickness, circumferential in 86.5% (32/37), and showed stratified enhancement in the enteric and portal phases in 91.9% (34/37) and 81.8% (9/11), respectively. Perienteric infiltration and prominent vasa recta were noted in 2.7% (1/37) and 13.5% (5/37), respectively. Bowel strictures were identified in six patients (66.7%), with a maximum upstream diameter of 31-48 mm. Two patients underwent surgery for strictures immediately after the initial enterography. Follow-up CTE and MRE in the remaining patients showed minimal-to-mild changes in the extent and thickness of the mural involvement for 17-138 months (median, 47.5 months) after initial enterography. Two patients required surgery for bowel stricture at 19 and 38 months of follow-up, respectively. Conclusion: CEAS of the small bowel typically manifested on enterography in varying numbers and lengths of abnormal ileal segments that showed circumferential mural thickening with layered enhancement without perienteric abnormalities. The lesions caused bowel strictures that required surgery in some patients.

• 한국재료학회지
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• 제22권6호
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• pp.303-308
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• 2012

This study evaluated the enhancement of microstructural and mechanical properties of a cross rolled Ni-10Cr alloy, comparing with conventionally rolled material. Cold rolling was carried out to 90% thickness reduction and the specimens were subsequently annealed at $700^{\circ}C$ for 30 min to obtain a fully recrystallized microstructure. Cross roll rolling was carried out at a tilted roll mill condition of $5^{\circ}$ from the transverse direction in the RD-TD plane. In order to observe the deformed microstructures of the cold rolled materials, transmission electron microscopy was employed. For annealed materials after rolling, in order to investigate the grain boundary characteristic distributions, an electron back-scattering diffraction technique was applied. Application of cold rolling to the Ni-10Cr alloy contributed to notable grain refinement, and consequently the average grain size was refined from 135 ${\mu}m$ in the initial material to 9.4 and 4.2 ${\mu}m$ in conventionally rolled and cross rolled materials, respectively, thus showing more significantly refined grains in the cross rolled material. This refined grain size led to enhanced mechanical properties such as yield and tensile strengths, with slightly higher values in the cross rolled material. Furthermore, the <111>//ND texture in the CRR material was better developed compared to that of the CR material, which contributed to enhanced mechanical properties and formability.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.376-376
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• 2012

Semiconductor nanowires (NWs) are future building block for nano-scale devices. Especially, Ge NWs are fascinated material due to the high electrical conductivity with high carrier mobility. It is strong candidate material for post-CMOS technology. However, thermal stability of Ge NWs are poor than conventional semiconductor material such as Si. Especially, when it reduced size as small as nano-scale it will be melted around CMOS process temperature due to the melting point depression. Recently, Graphene have been intensively interested since it has high carrier mobility with single atomic thickness. In addition, it is chemically very stable due to the $sp^2$ hybridization. Graphene films shows good protecting layer for oxidation resistance and corrosion resistance of metal surface using its chemical properties. Recently, we successfully demonstrated CVD growth of monolayer graphene using Ge catalyst. Using our growth method, we synthesized Ge/graphene core/shell (Ge@G) NW and conducted it for highly thermal stability required devices. We confirm the existence of graphene shell and morphology of NWs using SEM, TEM and Raman spectra. SEM and TEM images clearly show very thin graphene shell. We annealed NWs in vacuum at high temperature. Our results indicated that surface melting phenomena of Ge NWs due to the high surface energy from curvature of NWs start around $550^{\circ}C$ which is $270^{\circ}C$ lower than bulk melting point. When we increases annealing temperature, tip of Ge NWs start to make sphere shape in order to reduce its surface energy. On the contrary, Ge@G NWs prevent surface melting of Ge NWs and no Ge spheres generated. Furthermore, we fabricated filed emission devices using pure Ge NWs and Ge@G NWs. Compare with pure Ge NWs, graphene protected Ge NWs show enhancement of reliability. This growth approach serves a thermal stability enhancement of semiconductor NWs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.153-153
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• 2009

We investigated the dependence of the memory margin of the Cap-less memory cell on the strain of top silicon channel layer and also compared kink effect of strained Cap-less memory cell with the conventional Cap-less memory cell. For comparison of the characteristic of the memory margin of Cap-less memory cell on the strain channel layer, Cap-less transistors were fabricated on fully depleted strained silicon-on-insulator of 0.73-% tensile strain and conventional silicon-on-insulator substrate. The thickness of channel layer was fabricated as 40 nm to obtain optimal memory margin. We obtained the enhancement of 2.12 times in the memory margin of Cap-less memory cell on strained-silicon-on-insulator substrate, compared with a conventional SOI substrate. In particular, much higher D1 current of Cap-less memory cell was observed, resulted from a higher drain conductance of 2.65 times at the kink region, induced by the 1.7 times higher electron mobility in the strain channel than the conventional Cap-less memory cell at the effective field of 0.3MV/cm. Enhancement of memory margin supports the strained Cap-less memory cell can be promising substrate structures to improve the characteristics of Cap-less memory cell.