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

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Laser Crystallization of a-Si:H films prepared at Ultra Low Temperature($<150^{\circ}C$) by Catalytic CVD

  • Lee, Sung-Hyun;Hong, Wan-Shick;Kim, Jong-Man;Lim, Hyuck;Park, Kuyng-Bae;Cho, Chul-Lae;Lee, Kyung-Eun;Kim, Do-Young;Jung, Ji-Sim;Kwon, Jang-Yeon;Noguch, Takashi
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1116-1118
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    • 2005
  • We studied laser crystallization of amorphous silicon films prepared at ultra low temperatures ($<150^{\circ}C$). Amorphous silicon films having a low content of hydrogen were deposited by using catalytic chemical vapor deposition method. Influence of process parameters on the hydrogen content was investigated. Laser crystallization was performed dispensing with the preliminary dehydrogenation process. Crystallization took place at a laser energy density value as low as 70mJ/cm2, and the grain size increased with increasing the laser energy. The ELA crystallization of Catalytic CVD a-Si film is a promising candidate for Poly-Si TFT in active-matrix flexible display on plastic substrates.

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Investigation on Electrical Property of Amorphous Oxide SiZnSnO Semiconducting Thin Films (비정질 산화물 SiZnSnO 반도체 박막의 전기적 특성 분석)

  • Byun, Jae Min;Lee, Sang Yeol
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.4
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    • pp.272-275
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    • 2019
  • We investigated the electrical characteristics of amorphous silicon-zinc-tin-oxide (a-SZTO) thin films deposited by RF-magnetron sputtering at room temperature depending on the deposition time. We fabricated a thin film transistor (TFT) with a bottom gate structure and various channel thicknesses. With increasing channel thickness, the threshold voltage shifted negatively from -0.44 V to -2.18 V, the on current (Ion) and field effect mobility (μFE) increased because of increasing carrier concentration. The a-SZTO film was fabricated and analyzed in terms of the contact resistance and channel resistance. In this study, the transmission line method (TLM) was adopted and investigated. With increasing channel thickness, the contact resistance and sheet resistance both decreased.

Surface Morphology and Grain Growth of LPCVD Polycrystalline Silicon (저압 화학 기상 증착법으로 제작한 다결정 실리콘의 표면 형태 및 결정 성장)

  • Lee, Eun-Gu;Park, Jin-Seong;Lee, Jae-Gap
    • Korean Journal of Materials Research
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    • v.5 no.2
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    • pp.197-202
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    • 1995
  • The surface morphology and grain growth of amophous silicon (a-Si) films deposited by low pressure chemical vapor deposition (LPCVD) have been investigated as a function of deposition and in sltu annealing condition. The film deposited at the amorphous to polycrystalline transition temperature has an extra-rough, rugged surface with (311) t.exture. At the same deposition temperature, the grain structure tends to shirr. from the polycrystalline to the amorphous phase with increasing the film thickness. It is found that nucleation of a-Si during in situ annealing at the transition temperature without breaking the vacuum starts to occur from surface Si atom migration in contrast to a heterogeneous nucleation during film deposition.

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Separating nanocluster Si formation and Er activation in nanocluster-Si sensitized Er luminescence

  • Kim, In-Yong;Sin, Jung-Hun;Kim, Gyeong-Jung
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.109-109
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    • 2010
  • Er3+ ion shows a stable and efficient luminescence at 1.54mm due to its 4I13/24I15/2 intra-4f transition. As this corresponds to the low-loss window of silica-based optical fibers, Er-based light sources have become a mainstay of the long-distance telecom. In most telecom applications, Er3+ ions are excited via resonant optical pumping. However, if nanocluster-Si (nc-Si) are co-doped with Er3+, Er3+ can be excited via energy transfer from excited electrical carriers in the nc-Si as well. This combines the broad, strong absorption band of nc-Si with narrow, stable emission spectra of Er3+ to allow top-pumping with off-resonant, low-cost broadband light sources as well as electrical pumping. A widely used method to achieve nc-Si sensitization of Er3+ is high-temperature annealing of Er-doped, non-stoichiometric amorphous thin film with excess Si (e.g.,silicon-rich silicon oxide(SRSO)) to precipitate nc-Si and optically activate Er3+ at the same time. Unfortunately, such precipitation and growth of nc-Si into Er-doped oxide matrix can lead to Er3+ clustering away from nc-Si at anneal temperatures much lower than 1000C that is necessary for full optical activation of Er3+ in SiO2. Recently, silicon-rich silicon nitride (SRSN) was reported to be a promising alternative to SRSO that can overcome this problem of Er clustering. But as nc-Si formation and optical activation Er3+ remain linked in Er-doped SRSN, it is not clear which mechanism is responsible for the observed improvement. In this paper, we report on investigating the effect of separating the nc-Si formation and Er3+ activation by using hetero-multilayers that consist of nm-thin SRSO or SRSN sensitizing layers with Er-doped SiO2 or Si3N4 luminescing layers.

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Influence of Channel Thickness Variation on Temperature and Bias Induced Stress Instability of Amorphous SiInZnO Thin Film Transistors

  • Lee, Byeong Hyeon;Lee, Sang Yeol
    • Transactions on Electrical and Electronic Materials
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    • v.18 no.1
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    • pp.51-54
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    • 2017
  • TFTs (thin film transistors) were fabricated using a-SIZO (amorphous silicon-indium-zinc-oxide) channel by RF (radio frequency) magnetron sputtering at room temperature. We report the influence of various channel thickness on the electrical performances of a-SIZO TFTs and their stability, using TS (temperature stress) and NBTS (negative bias temperature stress). Channel thickness was controlled by changing the deposition time. As the channel thickness increased, the threshold voltage (VTH) of a-SIZO changed to the negative direction, from 1.3 to -2.4 V. This is mainly due to the increase of carrier concentration. During TS and NBTS, the threshold voltage shift (ΔVTH) increased steadily, with increasing channel thickness. These results can be explained by the total trap density (NT) increase due to the increase of bulk trap density (NBulk) in a-SIZO channel layer.

Fabrication and Characterization of a-Si:H Films by a Remote Plasma Enhanced CVD (Remote Plasma Enhanced CVD에 의한 수소화된 비정질 실리콘 박막의 제작 및 특성연구)

  • Yang, Young-Sik;Yoon, Yeer-Jean;Jang, Jin
    • Proceedings of the KIEE Conference
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    • 1987.07a
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    • pp.513-516
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    • 1987
  • Hydrogenated amorphous silicon (a-Si:H) films have been deposited, for thye first time, by a remote plasma chemical vapor deposition. The hydrogen radical play a important role to control the deposition rate, The bonded hydrogen content to silicon is independent of hydrogen partial pressure in the plasma. Optical gap of deposited a-Si:H lies between 1.7eV and 1.8eV and all samples have sharp absorption edge. B-doped a-Si:H films by a RPECVD has a high doping efficiency compared with plasma CVD. The Fermi level of 100ppm B-doped film lies at 0.5eV above valence band edge.

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Thin film solar cells (박막형 태양전지)

  • 김동섭;이수홍
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.5 no.1
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    • pp.67-77
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    • 1995
  • Abstract The principal factor affecting the increased penetration of photovoltaics into the marketplace is cost. For traditional crystalline silicon modules, half of the cost is that of the silicon wafers. As a result much effort has centered on reducing this cost by the use of thin film technologies. Substantial technical progress has been made towards improving the efficiencies of polycrystalline thin film solar cells to reduce the production costs. Progress in semiconductor deposition techniques has also been rapid. The most mature of these are based on polycrystalline silicon (p - Si), amorphous silicon (a - Si), copper indium diselenide SuInSe2(CIS), and cadmium telluride (CdTe). This paper explores the recent advances in the development of polycrystalline thin film solar cells.

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Formation and Photoluminescence of Silicon Oxide Nanowires by Thermal Treatment of Nickel Nanoparticles Deposited on the Silicon Wafer

  • Jang, Seon-Hui;Lee, Yeong-Il;Kim, Dong-Hun
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2011.10a
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    • pp.27.1-27.1
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    • 2011
  • The recent extensive research of one-dimensional (1D) nanostructures such as nanowires (NWs) and nanotubes (NTs) has been the driving force to fabricate new kinds of nanoscale devices in electronics, optics and bioengineering. We attempt to produce silicon oxide nanowires (SiOxNWs) in a simple way without complicate deposition process, gaseous Si containing precursors, or starting material of SiO2. Nickel (Ni) nanoparticles (NPs) were applied on Si wafer and thermally treated in a furnace. The temperature in the furnace was kept in the ranges between 900 and 1,100C and a mixture of nitrogen (N2) and hydrogen (H2) flowed through the furnace. The SiOxNWs had widths ranging from 100 to 200 nm with length extending up to ~10 μm and their structure was amorphous. Ni NPs were acted as catalysts. Since there were no other Si materials introduced into the furnace, the Si wafer was the only Si sources for the growth of SiOxNWs. When the Si wafer with deposition of Ni NPs was heated, the liquid Ni-Si alloy droplets were formed. The droplets as the nucleation sites induce an initiation of the growth of SiOxNWs and absorb oxygen easily. As the droplets became supersaturated, the SiOxNWs were grown, by the reaction between Si and O and continuously dissolving Si and O onto NPs. Photoluminescence (PL) showed that blue emission spectrum was centered at the wavelength of 450 nm (2.76 eV). The details of growth mechanism of SiOxNWs and the effect of Ni NPs on the formation of SiOxNWs will be presented.

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Electrical Properties of Boron-Doped Amorphous Silicon Ambipolar Thin Film Transistor (보론 도우핑된 비정질 실리콘을 이용한 쌍극 박막 트랜지스터의 전기적 특성)

  • Chu, Hye-Yong;Jang, Jin
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.5
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    • pp.38-45
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    • 1989
  • We have studied the electrical characteristics of the hydrogenated amorphous silicon (a-Si:H) ambiploar thin film transistors (TET'S)using 100ppm boron-doped a-Si:H as an active layer. The enhancement of drain current due to the double injection behavior has been observed in the p-channel operation of the TFT. The drain current decreases with time in streched exponential form when the gate voltage is positive. The result indicates that the dangling bonds created by electron accumulation show identical time dependence as the diffusion of hydrogen in the film. We observed the experimental evidence that the doping efficiency changes either when the gate bias is applied or when the light is illuminated on boron-doped a-Si:H.

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Enhanced Crystallization of Amorphous Si Using viscous Ni Solution and Microwave Annealing

  • Ahn, Jin-Hyung;Eom, Ji-Hye;Ahn, Byung-Tae
    • Journal of Information Display
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    • v.2 no.2
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    • pp.7-12
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    • 2001
  • A viscous Ni solution was coated over amorphous Si thin film for evenly spread of Ni metal source. The Ni s. prepared by dissolving NiCl2 into IN HCI and mixing with propylene glycol. NiCl2 and Ni were deposited on the amorphous film after oven dry and they enabled to obtain a uniform crystallization. The crystallization using the viscous Ni solution was a Ni-silicide mediated process, the same process used with Ni metal layer. The crystallization temperature was lowered to 480C by the synergy effect of silicide-mediated crystallization and microwave-induced crystallization. Lateral crystallization was also enhanced such that the velocity of lateral crystallization by microwave annealing became faster than by furnace annealing.

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