• Title/Summary/Keyword: amorphous silicon (a-Si)

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Operating Characteristics of Amorphous GeSe-based Resistive Random Access Memory at Metal-Insulator-Silicon Structure (금속-절연층-실리콘 구조에서의 비정질 GeSe 기반 Resistive Random Access Memory의 동작 특성)

  • Nam, Ki-Hyun;Kim, Jang-Han;Chung, Hong-Bay
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.7
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    • pp.400-403
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    • 2016
  • The resistive memory switching characteristics of resistive random access memory (ReRAM) using the amorphous GeSe thin film have been demonstrated at Al/Ti/GeSe/n+ poly Si structure. This ReRAM indicated bipolar resistive memory switching characteristics. The generation and the recombination of chalcogen cations and anions were suitable to explain the bipolar switching operation. Space charge limited current (SCLC) model and Poole-Frenkel emission is applied to explain the formation of conductive filament in the amorphous GeSe thin film. The results showed characteristics of stable switching and excellent reliability. Through the annealing condition of 400C, the possibility of low temperature process was established. Very low operation current level (set current: ~ μA, reset current: ~ nA) was showed the possibility of low power consumption. Particularly, n+ poly Si based GeSe ReRAM could be applied directly to thin film transistor (TFT).

Development of a Low Temperature Doping Technique for Applications in Poly-Si TFT on Plastic Substrates

  • Hong, Wan-Shick;Kim, Jong-Man
    • Journal of Information Display
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    • v.4 no.3
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    • pp.17-21
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    • 2003
  • A low temperature doping technique to be applied in poly-Si TFTs on plastic substrates was investigated. Heavily-doped amorphous silicon layers were deposited on poly-Si and the dopant atoms were driven in by subsequent excimer laser annealing. The entire process was carried out under a substrate temperature of 120 C, and a sheet resistance of as low as 300 Ω/sq. was obtained.

THE TWO-STEP RAPID THERMAL ANNEALING EFFECT OF THE PREPATTERNED A-SI FILMS (프리 패턴한 비정질 실리콘 박막의 two-step RTA 효과)

  • Lee, Min-Cheol;Park, Kee-Chan;Choi, Kwon-Young;Han, Min-Koo
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1333-1336
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    • 1998
  • Hydrogenated amorphous silicon(a-Si:H) films which were deposited by plasma enhanced chemical deposition(PECVD) have been recrystallized by the two-step rapid thermal annealing(RTA) employing the halogen lamp. The a-Si:H films evolve hydrogen explosively during the high temperature crystallzation step. In result, the recrystallized polycrystalline silicon(poly-Si) films have poor surface morphology. In order to avoid the hydrogen evolution, the films have undergone the dehydrogenation step prior to the crystallization step Before the RTA process, the active area of thin film transistors (TFT's) was patterned. The prepatterning of the a-Si:H active islands may reduce thermal damage to the glass substrate during the recrystallization. The computer generated simulation shows the heat propagation from the a-Si:H islands into the glass substrate. We have fabricated the poly-Si TFT's on the silicon wafers. The maximun ON/OFF current ratio of the device was over 105.

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Development of Nano Crystal Embedded Polymorphous Silicon Thin Film by Neutral Beam Assisted CVD Process at Room Temperature

  • Jang, Jin-Nyoung;Lee, Dong-Hyeok;So, Hyun-Wook;Yoo, Suk-Jae;Lee, Bon-Ju;Hong, Mun-Pyo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.02a
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    • pp.171-171
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    • 2012
  • Neutral beam assisted chemical vapor deposition (NBa-CVD) process has been developed as a nove,l room temperature deposition process for the light-soaking free nano-crystalline silicon (nc-Si) thin films including intrinsic and n-type doped thin film. During formation of nc-Si thin films by the NBa-CVD process with silicon reflector at room temperature, the energetic particles enhance doping efficiency and crystalline phase in nc-Si thin films without additional heating at substrate. The effects of incident NB energy controlled by the reflector bias have been confirmed by Raman spectra analysis. Additionally, TEM images show uniform nc-Si grains which imbedded amorphous phase without incubation layer. The nc-Si films by the NBa-CVD are hardly degenerated by light soaking; the degradations of photoconductivity were just a few percents before and after light irradiation.

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Effect of substrate temperature and hydrogen dilution on solid-phase crystallization of plasma-enhanced chemical vapor deposited amorphous silicon films (PECVD로 증착된 a-Si박막의 고상결정화에 있어서 기판 온도 및 수소희석의 효과)

  • 이정근
    • Journal of the Korean Vacuum Society
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    • v.7 no.1
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    • pp.29-34
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    • 1998
  • The solid-phase crystallization (SPC) of plasma-enhanced chemical vapor depsoited (PECVD) amorphous silicon (a-Si) films ha s been investigated by x-ray diffraction (XRD). The a-Si films were prepared on Si (100) wafers using SiH4 gas and without H2 dilution at the substrate temperatures between 120C and 380C, and than annealed at 600C for crystallization. The annealed samples exhibited (111), (220), and (311) XRD peaks with preferential orientation of (111). The XRD peak intensities increased as the substrate temperature decreased, and the H2dilution suppressed the solid-phase crystallization. The average grain size estimated by XRD analysis for the (111) texture has increased from about 10 nm to about 30 nm, as the substrate temperature decreased. The deposition rate also increased with the decreasing substrate temperature and the grain size was closely dependent on the deposition rate of the films. The grain size enhancement was attributed to an increase of the structural disorder of the Si network.

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Silicon Prism-based NIR Spectrometer Utilizing MEMS Technology

  • Jung, Dong Geon;Son, Su Hee;Kwon, Sun Young;Lee, Jun Yeop;Kong, Seong Ho
    • Journal of Sensor Science and Technology
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    • v.26 no.2
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    • pp.91-95
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    • 2017
  • Recently, infrared (IR) spectrometers have been required in various fields such as environment, safety, mobile, automotive, and military. This IR dispersive sensor detection method of substances is widely used. In this study, we fabricated a silicon (Si) prism-based near infrared (NIR) spectrometer utilizing micro electro mechanical system (MEMS) technology. Si prism-based NIR spectrometer utilizing MEMS technology consists of upper, middle, and lower substrates. The upper substrate passes through the incident IR ray selectively. The middle substrate, acting as a prism, disperses and separates the incident IR beam. The lower substrate has an amorphous Si (a-Si)-based bolometer array to detect the IR spectrum. The fabricated Si prism-based NIR spectrometer utilizing MEMS technology has the advantage of a simple structure, easy fabrication steps, and a wide NIR region operating range.

Epitaxial Growth of CoSi2 Layer on (100)Si Substrate using CoNx Interlayer deposited by Reactive Sputtering (반응성 스퍼터링법으로 증착된 CoNx 중간층을 이용한 (100)Si 기판 위에서의 에피택셜 CoSi2 성장 연구)

  • Lee, Seung-Ryul;Kim, Sun-Il;Ahn, Byung-Tae
    • Korean Journal of Materials Research
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    • v.16 no.1
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    • pp.30-36
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    • 2006
  • A novel method was proposed to grow an epitaxial CoSi2 on (100)Si substrate. A CoNx interlayer was deposited by reactive sputtering of Co in an Ar+N2 flow. From the Ti/Co/CoNx/Si structure, a uniform and thin CoSi2 layer was epitaxially grown on (100)Si by annealing above 700C. Two amorphous layers were found at the CoNx/Si interface, where the top layer has a silicon nitride (Si-N) bonding state with some Co content and the bottom layer has a Co-Si intermixing state. The SiNx amorphous layer seems to play a critical role of suppressing the diffusion of Co into Si substrate for the direct formation of epitaxial CoSi2.

Layer-by-layer nitrogenation of microcrystalline silicon for TFT applications

  • Bu, I.;Milne, W.I.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.405-407
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    • 2004
  • We have optimized the low temperature growth of microcrystalline silicon at 80C. This material has been used to fabricate bottom gate μc-Si:H TFTs by using a layer-by-layer nitrogenation process. By using this process the amorphous incubation layer can be converted into silicon nitride and leads to an increase in field effect mobility of the TFT

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Surface and Structural Features of a-Si Thin Films Prepared by Various H2/H2+SiH4 Dilution (수소 가스 분율(H2/H2+SiH4)에 따른 비정질 실리콘 박막의 표면 및 구조 분석)

  • Kwon, Jin-Up
    • Journal of Surface Science and Engineering
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    • v.44 no.2
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    • pp.39-43
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    • 2011
  • Amorphous silicon thin film was deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD). Each films were prepared in different dilution in the chamber gas. As a result, silicon crystallites and crystal volume fraction was increased with raising the hydrogen dilution in the gas and optical band gap was decreased. Increasement of the hydrogen contents in the chamber affected on surface roughness. In this study, thickness and surface roughness of the a-Si thin film by different hydrogen dilution was investigated by various techniques.

Effect of Carbon-coated Silicon/Graphite Composite Anode on the Electrochemical Properties

  • Kim, Hyung-Sun;Chung, Kyung-Yoon;Cho, Byung-Won
    • Bulletin of the Korean Chemical Society
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    • v.29 no.10
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    • pp.1965-1968
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    • 2008
  • The effects of carbon-coated silicon/graphite (Si/Gr.) composite anode on the electrochemical properties were investigated. The nanosized silicon particle shows a good cycling performance with a reasonable value of the first reversible capacity as compared with microsized silicon particle. The carbon-coated silicon/graphite composite powders have been prepared by pyrolysis method under argon/10 wt% propylene gas flow at 700C for 7 h. Transmission electron microscopy (TEM) analysis indicates that the carbon layer thickness of 5 nm was coated uniformly onto the surface silicon powder. It is confirmed that the insertion of lithium ions change the crystalline silicon phase into the amorphous phase by X-ray diffraction (XRD) analysis. The carbon-coated composite silicon/graphite anode shows excellent cycling performance with a reversible value of 700 mAh/g. The superior electrochemical characteristics are attributed to the enhanced electronic conductivity and low volume change of silicon powder during cycling by carbon coating.